Custom object design and building choices

Though the grid is limited to 8x8x8 by default, and you only seem to get 5 colors (3 in the demo), there's still a lot of potential for making custom objects, or even custom buildings out of modules, existing or custom.
With that in mind, it would be nice to be able to make designs for custom modules and/or buildings in a seperate UI that's either accessible in-game or from the main menu (and if from the main menu, to be able to at least pin custom modules in-game).
It would be fully understandable if these features were locked behind a setting for a save that makes it invalid for achievements, but it would still be nice; that way, you could more easily have community challenges for not just designing art that's in-game, but even automating the production of it! This would give an alternative set of challenges or goals for people to do if they want a break from the game-made modules and challenges.
Additionally, if giving the option of making custom buildings out of modules, it could be fun to make custom city-scapes out of hand-made modules and buildings.

While all of this wouldn't neccessarily have much of any use in normal gameplay, it would give an interesting, alternative gameplay that I think would be very unique and encourage more user-built creations, both with factories and modules.