This is an evolution of the OpenSCAD rewrite by "toomanyplugs" of "bubak"'s original OpenX carriage. This version includes:captive nut traps for most of the horizontal holes more parametric variables (not completely finished) thicker cross beams and outer edge (to accommodate captive nuts) wider hole on the back clamp to feed x-axis belt through (see update after printing)Updated version: Shorter incomplete polygons. Should only be 3-4 layers of trick holes depending on your layer height.Update after printing: Putting the belt through the undercarriage arm hole doesn't work. The belt rubs against the rods too much as there isn't enough clearance. For now, I just used the two block from my Sell's carriage to pinch the belt and screwed that into one of the available holes in this openx carriage. It works quite well.Update again: Huzzah! jkeegan made the arm in OpenSCADhttp://www.thingiverse.com/thing:17971Use OpenSCAD to generate STLs for the carriage body and the undercarriage arm. Use the front mounting arm from the original thing.Probably best to print with 1 extra shell and 40% or more infill.If your x-axis belt is not split and you want to keep it that way, use the blocks from the Sell's x-carriage to pinch the belt at the desired tension and screw one end of those blocks onto the carriage.