Spring Loaded Gantry/Slider

This is intended as part of of an xycore plotter. The original 2020 drawbot is here:
https://www.thingiverse.com/thing:2374238

I expanded this to be 8'x4' but the rails kept sticking, so I made a roller version inspired by:
https://www.thingiverse.com/thing:1329733

I used openscad to merge the two into a spring-loaded carriage gantry that fit snugly onto a normal 20mmx20mm extrusion.

Update: This didn't actually work very well because the sizing is off. Proof in concept only.