This is a pulley set design for the Cyclone PCB, though it could be used in other applications. Pulley #1 is designed to clamp to an 8mm lead screw (or threaded rod). Pulley #2 attaches to a standard 5mm stepper d-shaft. The M3 captive nuts are designed to be heat staked with a soldering iron.
There are a few other cyclone pulleys out there, but I wasn't happy with all the dimensions on any of them. So I redesigned these from scratch. I have also added step files for easier modification.
I use them with 160mm x 9mm GT2 belts.