About this 3D model
This is my caliper. There are many like it, but this one is mine. Rack and pinion from: http://www.thingiverse.com/thing:944471Screw and bolt from: http://www.thingiverse.com/thing:1183 Note, the screw is left-handed, so that CCW rotation to open the calipers will tighten the bolt. This is intentional. When you go to screw it on, remember "lefty-tighty, righty-loosey". Built in Tinkercad. Edit your own: https://tinkercad.com/things/1hsFTJBqkhA