I wanted to change the idler for the X axis. Unfortunately, I only had one with 20 teeth, which had a larger diameter (18 mm OD). I have adapted the printed part accordingly. (I have also enlarged the cutout a little further to make it easier to install the belt)
Please test/use at your own risk, as the inner diameter is also slightly larger. It works fine for me so far. It can be printed with the recommended settings from RatRig.
v2 is not yet tested, but I have only adapted the opening a little better to the overall design
The author hasn't provided the model origin yet.