Been after a tensioner for my core XY belts for a while, never found anything that I liked or would work with my setup. Decided to build my own.
A few hours on fusion 360 and here we are. I have a backboard on my core XY that the part will screw to. Then it's a simple case of adjusting the 2 cogs to the required tension and lock it in place with the screw and bolt.
Included both stl and 3mf files and also added a stl of the components of the full design.
The author hasn't provided the model origin yet.