Adjustable belt tensioner for GT2 belts. Strongly based on ThomasKTN Belt shortener for Ultimaker, it features a clip to lock the main part and press the belt tightly.It uses a DIN912 M3x35 bolt (or longer, if you will) and 2xM3 nuts (one used to counter-lock the other). Just print a pair of each piece, place the screw, fit the belt and lock with the clip. I added the .skp of the clip, so you can make little adjustments if your printed part requires so.