The belt tensioners are a great model. I printed these in ABS on my Prusa i3 MK2.5 and came out very nice. Surprised how well the different pieces fit together.
Unfortunately I had the tensioner puller broken twice: First time when I applied too much tension it snapped. This was with 20% infill. Then I decided to make the infill 100%. The second time I broke it myself when checking the rigidity.
Perhaps for the design it would be better to add a fillet between the inner flat plateau and the standing brackets. There is not much material at this intersection making it easy to break.
Fillamentum Extrafill ABS 1.75mm