I don't think the 3D printed wheels will last long - all the 3D printed antweights that I have seen broke after a few fights, including nylon ones printed on pro machines by Shapeways. Give it a go, but also think of a plan B just in case.

Making printed carriers for electronics works very well, I haven't had anything die from shock damage in several years.

I'm guessing that the blue spacers are plastic. Would it be possible to replace them with a custom sized aluminium nutstrip? That would save space internally and provide a much stronger attachment between the outside bulkheads and the rest of the frame.