GT2 Pulley (customizable with *.f3d)

Download the Fusion 360 file and enter your custom dimensions. In the Design Workspace, use Modify, Change parameters. If your changes break the design, try smaller incremental updates.

There is already a working implementation of 'gt2 pulleys' on Thingiverse. Nonetheless, that implementation is based on SCAD, which results in mesh files. If you prefer to model project parts directly in Fusion 360, this thing is for you!

It took me quite some time to get my head around the math behind the grooves. Contrary to popular belief, the profile is not just an inverse of the belt's teeth. It would be that way for a belt wrapped around a pulley, but not when the belt leaves the circumference at some point. For any given rotation, belt and pulley cover the same distance, the belt in a tangential line and the pulley in a circular path around its center. The grooves profile has to account for the deviation. The mathematical concept to describe this relative change is called Involute. Have a look at the attached Fusion 360 file to get an idea of how it works.

If you have doubts about this tooth profile, I would love to discuss them in the comments. (e.g., contact surface vs. clearance)