I agree, Octavio. When I saw the original render, I thought it was using a screw drive and thought it would be slow and complicated, but the rack and pinion system is actually pretty slick.

The racks are made of a plastic to keep friction down then? I understand that the prints aren't terribly heavy, but with it moving at that speed up and down the pinion, you'll likely end up with pretty fast wear on the racks. Though I assume the build platform is pretty easy to replace when those racks do eventually wear down (buying more than one build plate probably isn't a bad idea, to start a new print while prying off/cleaning up after the finished one.) I guess I didn't think of just placing the tray in the corner of the box. What kind of positioning sensor or end stops do you have planned for it? Or does it even need them if it assumes you put the plate in the same "home" corner every time?