Nema motor shaft coupler / fitting

This is a simple fitting/couping for the Nema 17 motor (don't know if it works for the Nema 23 as well). I was making the "Simple filament extruder puller by james_III" and found some rubber wheels that had a 7mm diameter hole, but my Nema 17 motor shaft had a 5mm diameter so I needed some sort of "tube" to make the shaft fit thight on the rubber wheel hole. On the files attached you will find an .STL ready to print, and I also included the 123D design source files in case you want to modify the