That's awesome, good luck with the space station kit! Getting the modular pieces to line up cleanly without gaps or overlaps is honestly the trickiest part -- took me a few rounds of testing everything in-engine before it clicked. Looking forward to seeing it once it's up!
And thank you! For the walls, I'm not assigning a material per polygon -- instead I built a shared trim sheet: one texture atlas with a few materials (stone, wood, metal) baked onto it, then I just adjust the UV mapping on each piece so it points to the right zone of that single texture. It's a lot more efficient since multiple assets can reuse the same texture without adding extra materials or draw calls. Since you're already doing per-polygon materials, you're most of the way there -- the trim sheet approach is really just about being smarter with your UVs rather than a totally different workflow. Happy to go into more detail if that'd help!