Which LEGO Technic fan by now has not heard of Madoca1977? Two years ago he burst onto the MOC scene with some of the best Technic MOCs the LEGO world had ever seen, and has been releasing excellent MOC after excellent MOC ever since.

Now, he has agreed to sit down with us folks at Rebrickable for an exclusive interview. Read on to learn all about the man behind the Madoca1977 moniker!

Click here to see all of Madoka's MOCs on Rebrickable.

Madoka with some of his MOCs

Thanks for having this interview with us, Madoka! First of all, can you tell us a bit about yourself? What is your work besides building LEGO Technic MOCs? Any other hobbies?

Hi! My name is Madoka Arai. I am 37 years old, and I live in Japan. I am a certified care worker working for a nursing home for the elderly. Five days a week I help the elderly move, eat, take a bath, etc. I spend most of my free time building Lego or watching movies. I like various kinds of movies, especially scary ones; my favorites are 1970's Dario Argento movies. I also like cars a lot. Every Sunday night (in Japan), I watch BBC's Top Gear. This show often inspires me to build car-related MOCs.

When was your first exposure to LEGO? Did you experience any so-called 'Dark Ages'? If so, what brought you back to LEGO?

I was about two years old when I first discovered LEGO in its DUPLO variant. Since then my parents have bought me many LEGO SYSTEM (LEGOLAND) sets. I was so fascinated with building. My favorite set was 928 Galaxy Explorer. Also I already built so-called MOCs using parts from different types of sets. 6000 LEGOLAND Idea Book was a treasure of inspiration. My first Technic set was 8050 Universal set. I was six years old and was excited to build functional models. I became a Technic builder since then. During my teenage years, I got 8851, 8855, 8865, 8835 and 8868. I did not build many Technic MOCs because the Technic style of building was a bit difficult for me at that age.

When I was around nineteen years old, I stopped playing with LEGO altogether. I started to spend most of my spare time with my PlayStation instead. For about a decade, I did not buy any Lego sets or parts. I did not even touch them. Hence, I completely missed the decade that Technic changed its building style from studful to studless. In 2010 I suddenly noticed that I can buy LEGO Technic sets on the internet. I was amazed at first to see studless sets like 8297 Off-Roader and 8258 Crane Truck. These sets are responsible for bringing me out of my Dark Ages: I bought both of them immediately, and then got many other sets which I had missed during my leave of absence, including the legendary 8480, 8448, 8285 and 8421.

Madoka's Wing Body Truck MOC

How big is your parts collection? How many sets do you own?

First of all, I only collect Technic sets and parts. I have no sets of any other LEGO theme. And the answer is… a LOT of parts and sets! I have never counted the numbers of parts or sets I own. After my Dark Ages, I bought most of the sets that I mentioned above at an auction site. They were very expensive because they had been released a long time ago, and most of them were classic sets.

Because of that, I decided from then on out to buy all the sets in their release year. That means I have all Technic sets released since 2011. Some of them are still unopened! Also I bought extra sets and hundreds of parts for building some MOCs. For instance, I bought four sets of 8110 and more than sixty loose LBG panels for creating the Wing Body Truck and its instructions. When 8070 was released, I bought three of them for the useful parts because I expected that TLG would not release a similar set (containing suspension arms, wheel hubs, angle connectors, bunch of panels and soft axles, etc.) in the next few years. I also have dozens of Power Functions elements. They are essential because I usually build motorized MOCs.

The last and foremost set that I want to mention is the exclusive 41999 Crawler. It is one of the few official sets that I put stickers on and it will stay assembled on the shelf.

Any favorite sets or parts? Why those in particular?

My favorite set is 9398 4x4 Crawler. I have built half of my creations using its L motors, servo motor and V2 receiver. For me, those elements are essential for building proper RC cars.

One of my favorite parts is 6553 Technic Pole Reverser Handle. It has both an axle and an axle hole. It is useful for connecting parts when there is only little room left, and the 1.5L axle enables half-stud assembly. I have used it in case of adjusting the location of body panels or for lowering the roof height a bit.

Another favorite part of mine is 92907 Technic Axle and Pin Connector Perpendicular Split. It can connect to other parts which have axle/pin holes using just one 2L axle, and the connection would never break apart without cracking the ABS. It is good for me because I prefer building with all the parts tightly connected as possible.

Are there any LEGO Technic parts you wish LEGO would develop? Similarly, are there any LEGO Technic sets you wish LEGO would release?

There are two types of parts that I want. One group is new elements. Smaller differential, wheel hub with planetary reduction, bigger actuator, etc. I know some expert builders have already made these parts by 3D printer. I am curious about that but do not plan to use custom parts because I am a purist. For now, my interest is to build playable RC model with an as effective and reliable drivetrain as possible using only official parts.

The other group is existing parts in different (rare) colors. Soft axles, angle connectors, toggle joints, panels, etc. Sometimes I have tried to build a MOC entirely in blue, orange or white, but I could not make it due to lack of those parts in that color. So the finished MOC was mostly in red or black. The good news is that TLG has produced various colors of panels in recent years. Now I desire soft axles and connectors in the same colors.

As for sets:

  • A motorized forklift. It has been a long time since last Technic forklift (not a mini set) was released. I like its mechanism and like watching the different forklift MOCs opearting on YouTube.
  • A massive off road vehicle, e.g. Avtoros Shaman 8x8. There are many MOCs of that kind of vehicle. I am very interested how TLG make those models by the rules of official set.


Any favorite MOCs by other MOC builders? Why those in particular?

My most favorite MOC is Sariel's Pagani Zonda. It is one of the fastest Lego cars. Perfectly designed for highest speed. I have much learned from his creations about possibilities and limitations of Lego parts. Another favorite is zblj's Fox 8x8x8. It showed me the answer for my question of what was the most effective drivetrain for a big and heavy 8x8 Lego trial truck (which I had wanted to build but not succeeded in 2013). I was deeply impressed, but at the same time did not want to copy it. So I tried to find another effective motor/gear combination. Finally, the project ended up as my Tatra 813 Trial Truck.

Madoka's Tatra 813 Trial Truck

Most of the well-known LEGO Technic MOC builders seem to hail from Europe or the USA. You are one notable exception (akiyuky is another, but builds GBC modules). Why do you think this is the case? Is LEGO Technic less popular in Asia/Japan? Or is this a language issue?

This is my personal opinion! I do not know how many Japanese Technic builders are known globally.

Do we (the Japanese) lack for (Technic) sets? Probably. In Japan, I think Lego (Technic) is not as popular as in Europe. It seems that there is no Lego Truck Trial Competition or similar events held in Japan. Maybe it is related to themarketing of TLG. In Japan, some sets of particular theme including 'Power Functions' are not available at LEGO.com.

Do we lack for (Technic) parts? I do not think so, though maybe I am in a minority. Building MOCs often requires some particular parts separately from several sets. In my case, I have never felt inconvenience of ordering sets or parts. I usually buy Technic sets at amazon.com. Usually they quickly delivered in one or two days in most cases. I often buy technic parts (in 'new' condition) separately at Japanese internet parts shops. Parts are delivered in three or four days. The prices are higher than BrickLink order, but it is easy to order, pay, delivered.

Do we lack the desire for building and sharing Technic MOCs? In my childhood, the only opportunity to know new Technic creation was to see the consumer catalogue, although that was adequately exciting for me. Today we can see thousands of awesome MOCs on the internet. Some of them have building instructions besides. I think the best Lego experience is to build by his own hand using actual parts. Some people build their own creations inspired from those awesomeness. Others build copies of someone's MOC by seeing instructions. Both of them grow their skills to build more complex/functional/beautiful creations. They share their new MOCs (on Rebrickable, Eurobricks, etc), and soon they will be known to many people. Then more people build, more creations are shared… This cycle is smaller in Japan.

Not all of the Japanese builders can read English. Translation software does not work well because the order of words in Japanese is different from many other languages. Sometimes it is hard to understand sentences on Lego community sites in English. This may be the reason why only few Japanese members are joining major international Lego communities. At the end of the day, in Japan there are less Technic builders, less Technic MOCs are built and shared. So less Japanese MOCs/builders are known to many people?

Do you prefer studless or studful building? Or a combination of both? LEGO seems to have moved away from using studful parts altogether in Technic sets, what is your opinion on that?

I prefer studless building for two reasons:

  • It enables us to use the space more efficiently. Normally we can put more Technic parts into the same size of models as the models of the 1980's. Which means today's models can have more functionality (and playability). I welcome the change.
  • It enables us to build a MOC using technic parts only. Compared to the system parts, the number of whole types of technic parts is small. And most of them are easily available by getting some official Technic sets. It is easier to build a MOC which is made out of less number of unique parts. Maybe that is why most of the 'Hottest MOCs' on Rebrickable are Technic builds. It is always challenging and enjoyable for me to build a model using (sort of) limited Technic elements.


Do you think the official LEGO Technic sets are changing for the worse or for the better throughout these past years? Any other aspects of LEGO that you like/dislike nowadays opposed to when you were younger?

I think that right now is the golden age of Technic sets in terms of aesthetics and functionality, in spite of not mimicking the mechanisms of actual vehicles accurately. I do not like the sets of around year 2000. They have many uncommon parts (including RC unit!) which are not produced in the 2010's. For me, a good set should be made out of ordinary parts which would keep being produced after ten years. If not, the set (and its parts) become antique and so expensive that only few people can buy or build. I am pretty sure that these liftarms, connectors and PF elements used in most of today's sets would be useful for building sets (and MOCs, more importantly) for more than a decade from now, because they are versatile. Good LEGO parts should be versatile. In other words, today's rare parts are expected to be still rare in 2020's unless TLG produces them and use in sets over and over.

Is there a good market for used parts and sets in Japan? If not, how do you acquire all the pieces you need to build your MOCs?

According to my quick search, there are more than ten shops selling new/used LEGO parts or sets. I usually buy parts from one of those shops. In Japan, the whole assortment of parts is not as wide as BrickLink worldwide. But that is enough for me because I order mostly common parts. Since I share building instructions of my models, I want to make MOCs out of ordinary parts which are easily available for everyone as possible.

You have stated on multiple occassions that you dream of becoming a LEGO designer. Have you ever had any contact with LEGO about your MOCs? Would you consider making less advanced MOCs that could pass the stringent LEGO Ideas selection, to catch LEGO's eye that way?

I have not had any contact with TLG. If I were mid twenties, I would certainly try to make contact with them. Even try to get a chance to work with them... Now I am 37 years old and have a nursing job. It is worth working and important for my life. For me, building LEGO models is not a job, but is the most favorite hobby. I enjoy building MOCs on my own without any deadlines.

About LEGO Ideas, I think my MOCs cannot pass the stage because they are essentially RC models which contain multiple expensive PF elements. What I want to do is build and share varieties of RC models which are not released so often by TLG. Though my MOCs are not released as official sets, anyone can build them along free building instructions. I am very pleased being called a custom set designer.

Madoka's Compact CUV and Blue Lightning Buggy

In the time the average MOC builder creates a single MOC, you manage to realize two or even three highly detailed MOCs. What is your secret? ;-)

I have no secret! I only have got multiple chances to realize my ideas.

Wing Body Truck:

It was an early creation and my biggest MOC for now. When I first built it, I did not know how to manage the whole project to the completion. On the other hand, the lack of experience enabled me to build freely without any plans. For six months, I kept building and buying more parts as I wanted. Then my room was filled with ridiculous amount of LBG panels, beams and PF wires. Although I was satisfying with the result, I could say it was something like once-in-a-lifetime building.

Tatra 813 Trial Truck:

After finishing the aforementioned Wing Body Truck in 2013, I built several mid scale MOCs which took about two month to finish. Then I wanted to build a bigger 'flagship MOC' for 2014. Though it was hard to build an effective drivetrain, I was able to calculate how to make it work and how to build the whole model systematically. So it took less than three months to finish the Tatra including instruction.

Future project: I want to build another big MOC in 2015... hopefully.

As stated before, your MOCs are highly detailed, and also offer intricate solutions to technical problems, while still being rugged and fully remotely controlled. Do you have an engineering background? If not, how do you come up with these solutions? Is it all self-taught?

All my engineering knowledge comes from the experience of building LEGO Technic. When I was a teenager, I learned from the set 8865 about gear ratios, differential, suspension, steering mechanism, etc. Later some studless sets taught me how to brace all the parts tightly. Some RC MOCs showed how to build proper drivetrain which can handle big torque. Since I like cars, I often see images of actual car chassis, suspension and drivetrain. It may help me building cars more accurately, but it is not the top priority for me. I prefer to build with the limitations of LEGO parts than to mimic actual mechanisms.

I usually decide the locations of essential parts (motors, bevel gears, driving axles) first, then build suitable structures around them and improve it over and over. I came up with most of these solutions in this iterating process.

As a followup to the previous question: what is the biggest Technic challenge you have had to deal with so far, and how did you solve it?

My biggest challenge so far was the drivetrain of my Tatra 813 Trial Truck. The Tatra's weight is 2800g. It is heavy enough for two XL motors (zblj's Fox is heavier, but it has eight XL motors for propulsion). To make the best use of the power of the two XL motors, I used three techniques:


  • Gearing down significantly. To increase the power, I used two different combinations of gears (12t bevel and 36t bevel gears, and 8t and 24t gear).
  • Installing a reliable heavy duty two speed gearbox. My first attempt by using a driving ring and 16t gear with clutch failed. Those parts got damaged and could not handle high torque. So I built my custom version of a heavy duty gearbox. It was a very solid structure and any gears in it did not slip.
  • Minimize the friction as much as possible. Unlike most Tatra MOCs, I did not set the pivots of the swing half axles on the central drive axle. Instead, I moved the pivots one stud outside of the central axle. Thus the central axle is free from the friction of the swing half axles. The real Tatra 813 has planetary hub reductions. I once built a LEGO planetary hub (which was using a large turntable and 8t gears) and felt that it generated more friction than portal hub. So I adopted portal hub reductions.


The result was not the best (looked slower than I expected), but was acceptable to me. Because all my creations are RC models, reliability is always important. My Tatra crawled well on rough terrain and successfully climbed very steep slopes without damaging any gears.

Most, if not all, of your models utilise the Power Functions (PF) system. Have you run into any problems with this technology or the individual elements? If so, how did you deal with that? What do you like/dislike about the PF system?

I like the PF system because it has a variety of elements and most of them are easy to get. Since PF elements have been produced for over seven years, we have plenty of spare parts available when they break. In other words, this is the main reason why I do not use rare RC buggy motors.

By the way, I really like the L motor in terms of design and performance. Since it has many pin holes, it is easy to connect tightly into Technic structure. It has good rpm for building fast RC models. It has enough torque for propelling models without damaging ABS parts. These are crucial properties for building proper RC models.

As we know, the most inconvenient thing is the maximum operating distance of the IR system, especially when it comes to outdoor driving. It is far too limited. I have accepted this though because I think it is a safety net for children who play LEGO outdoor. Imagine a boy operating his RC model. It goes away from him and crosses the main street. He may chase it by crossing the street carelessly... After all, LEGO should be more suitable for children than adults, and this IR system is well designed and works properly indoor.

But I am a grown up child. I need a better system for my RC models.

Have you heard about the SBrick? What is your opinion on it? Will you make use of it in your own MOCs?

Do you remember the movie '007 Tomorrow Never Dies'? In the film, Bond controlled his BMW using a touchpad on his phone. "Wow, we can finally make our own LEGO Bond car and drive it anywhere!" That was my first impression when I heard about SBrick.

Anyway, the SBrick is better than the current IR system, especially when you build RC models. You can control your models from a further distance with more precision. As a RC LEGO car builder, I have been waiting for such a higher performance device. I welcome the rise of SBrick models, but I have not purchased one yet.

For me, the only problem is that SBrick is not a product of TLG. Since I have been a LEGO purist, all my creations were made out of 100% LEGO original parts. "How far can I go only using pure LEGO parts?" That is my philosophy and motivation of building. However, I am planning to purchase a few SBricks and use them on my future projects. But I think the 'finished' models will be made purely out of official LEGO parts. Any SBrick versions will be limited editions. Someday I will probably change my mind and build models specifically for SBrick, but not now.

Madoka's Corvette C3 and AWD SUV

What is your opinion on Rebrickable? Do you use it yourself?

As a Technic builder I think Rebrickable is a very useful and inspiring site. Technic models contain many physical techniques both for mechanical functions and structural assembly. That means, the way and process of how to connect individual parts is as crucial as how the finished whole model looks. The best way to understand Technic models is to build them by connecting actual parts. The hundreds of building instructions available on Rebrickable enable a fan to build models accurately and help understanding. Then he probably becomes a newdesigner of his own creations. This process is not only interesting but also educational.

Rebrickable also shares with us various interesting data such as the parts list of a specific MOC, what MOCs you can build from your parts collection, etc. The most interesting thing which I learned about from Rebrickable is the 'Hottest MOC' feature. Most of them are usually Technic models. That is delightful. In my opinion, Technic models embody LEGO's philosophy truly because they are made out of basic-shaped parts (unlike recent system sets!). I think Rebrickable plays an important role in carrying out this philosophy.

Finally, do you have any tips for aspiring MOC builders, who wish to become as skilled as you?

From my experiences, I can say do-it-yourself building is good for developing your skills. I have built most of Technic sets released since 2010 and some MOCs which have building instructions. I have learned lots of effective, authentic, unexpected and enjoyable building techniques, even in official sets built with the TLG rules.

When it comes to building MOCs, I set basic rules for every project. And these rules follow from my extensive building experiences. Some of these rules are:

  • Use suitable motors for required torque.
  • Ensure that all functional axles cannot slip out.
  • Ensure all gears engage well and cannot break parts (U-Joints!) or other structures.
  • Brace all the parts tightly with two more connection point.
  • For adjustments of very small distance, connect parts using non-friction pins (do not bend any solid parts).
  • Adopt a particular color scheme for every single element.
  • Keep searching for the best location of all parts and keep improving the connections among them, etc.

These rules help to make the MOC better in terms of both functionality and aesthetics. Ofcourse, sometimes it is fun to build beyond the rules.


When the project has a problem which forces me to stop building, I usually do not look up the LEGO solution on the internet. Instead, I draw inspiration by looking at photos of a real car chassis, for instance, because I like inventing something new to me as much as building it. It is not important whether it has been made by someone else or not. The most important thing for me is to come up with the solution by myself. I believe this is one of the best experiences one can have when building with LEGO Technic. And it is good for improving building skills, too. On the other hand, I might miss better solutions than mine though... Occasionally this way of building causes similarities between my 'new' creation and someone's past creation. Then I feel something like empathy with the builder.

Since I am not very skilled with computers, I build LEGO only 'physically'. A welcome consequence is that it always ensures that the models I build work properly in real life. Regarding my RC MOCs, I have tried incorporating more effective and efficient drivetrains in them every time.

Thanks to the points above, I am sure I can now build better than I did three years ago. It is good for innovation to share knowledge and creations with each other. Recently I saw the news that Toyota opened its hydrogen patent. The first thought that came to me was that it was like sharing building instructions. In the LEGO community, I hope more people will build and share their creations, and get to know each other!

Thanks again for the interview Madoka, and we look forward to seeing more excellent MOCs from you!

Click here to see all of Madoka's MOCs on Rebrickable.


  • 2 years, 2 months ago Mysh Level 11
    Madoca, we know that many of your builds have been commercially abused by copycats during the past two years. But I still hope to see some of your terrific new designs again at rebrickable one day. If we stop sharing it's like they beat us. Thank you so much.
  • 4 years, 1 month ago Techno100 Level 6
    I was only thinking yesterday I wonder what Madoca is like and low and behold I came across this interview with the brightest star Madoka. A privilege indeed and how lucky are we that you speak English so very very well.
    Thank you
  • 4 years, 9 months ago KINGZAC24 Level 10 MOC Designer
    great job any chance you could make a moc for 42039 i have made an apc with it
  • 4 years, 10 months ago thirdwigg Level 16 MOC Designer
    Thanks for giving space for this wonderful interview. These are great questions, and the responses are full and thoughtful. I enjoyed the reading, and I was looking for more. Keep doing these. They are great.
  • 4 years, 10 months ago Wolf01 Level 13 MOC Designer
    I almost finished to build a Technic MOC with the beams (I'm from the old school) and I had very bad times trying to understand how to build with beams, like "think the structure first" and "how to connect this piece if the holes are 90° off?".
    I really fall in love with the beam Technic MOCs because I like the aesthetic.
    Good work Madoka!
  • 4 years, 10 months ago MocJens Level 9
    I love your MOCs madoca1977, at the moment I´m rebuilding the tatra 813...
  • 4 years, 10 months ago hoogie35 Level 9
    you are the man. great MOC's. nice interview
  • 4 years, 10 months ago DLuders Level 20 MOC Designer
    I think that The Lego Group should produce official Technic sets that are as good-looking and functional as Madoca's MOCs. In the meantime, he is very gracious in sharing his Building Instructions here on Rebrickable.
    • 4 years, 8 months ago skylandwalker Level 7
      I quite agree with you. He is a very great guy willing to share so terrific masterpieces with us. Thank him so much and hope he keeps on moving.
      • 3 years, 8 months ago asiadream Level 13
        Yes, He is great! Not many guys are willing to share their instructions.
  • 4 years, 10 months ago nxt45 Level 10 MOC Designer
    Quote: "Every Sunday night (in Japan), I watch BBC's Top Gear. This show often inspires me to build car-related MOCs."
    I really like that show!
  • 4 years, 10 months ago JEPPO Level 12 MOC Designer
    Do you keep all of your MOCs assembled?
    Great interview as well!
  • 4 years, 10 months ago Scapuc Level 11
    I built almost all your Moc and I want to thank you for sharing with us your work.
    To me you are a genius !!!
  • 4 years, 10 months ago 8987846 Level 3
    I really like the Tatra 813 Trial Truck and this is what gets me into lego world.
  • 4 years, 10 months ago psmyth Level 16
    Terrific interview...I have built most of his MOC's and they are all great. I will do his new one soon ....have to finish M_longers dump truck first!!
  • 4 years, 10 months ago martijnnab Level 13 MOC Designer
    Great interview with one of my big examples for Technic MOC creation!!
  • 4 years, 10 months ago ifilin Level 13
    Thank You very much Madoka and Jantjeuh for the great interview!
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