Getting 160*160*80mm total dimensions sounds juicy, but as I've mentioned before, the 192mm tiles are overal just a better option. Thinking about it, what sounds jucier is a solution that's even slimmer than 80mm, and 64 is a factor of 192.
All 5 motos would have to be placed flat as, excluding the 18mm LED matrix and 1mm clearance gap, I'd only have 45mm of real estate. That's only 10mm more than the width of the motors themselves.
I'm also thinking of using mineral oil, like in bike brakes, instead of fiber thread. I just imagine that the axes would be stiffer and more precise. In either case, I still have to worry about Axis1 and Axis5 since they have near or over 360 degree axis limits.
That brings me to my next question; should I give in to the slip rings?
It seems like they're an okayish size for an okayish price these days. Axis1 only really needs to travel 270 degrees, so the cable management shouldn't be an issue there, but after 3.5 years, I still haven't thought up a decent solution for Axis5.
The idea would be to send 36V power through 2 pins and data-in through 2 pins. Assuming 14 bits per channel, that should only be 1.23 MB of bandwidth required. Perhaps only 1 data pin would be necessary. On the LED matrix side, there'd be components to convert the 36V and data into 5v and HUB75.