A colony ship for Mars.
Featuring rotating habitat sections, a thick bulkhead separating the nuclear engine and a null-weight bridge with four portholes.
The spring-loaded action is thought of as the flywheel, which absorbs the spin of the habitats when the ship needs to be null-gravity all around (for landing for example.
For the source of idea and data is Arthur C. Clark's "A Space Odyssey"
Part 12799 (the Spring-loaded part) is not supported by LDD. Is it replaced by orange bricks in the LXF. Apologies.
Enjoy, Comments and suggestions welcome