This is a simple belt tensioner made by 3d0g. I've made the following changes: Reworked slot and teeth to fit GT2 2mm pitch belt. Added a third screw to clamp tighter around on belt. Thickened sides a bit around nut. Rounded the edges to the slot to make it easier to insert belt When tightening, I found it kept wanting to pivot and not pull away from the printer body. I addressed that by adding nuts to the end of the screws for a more stable "foot" and pulling the loose cable end up and over, fastening it to the printer with a cable tie. This pivoting inspired me to design this: http://www.thingiverse.com/thing:82388