I ordered a uStepper S-Lite integrated stepper motor driver and it came with a mount for a Nema17 stepper motor - I needed one for the Nema23 that came with my OpenBuilds C gantry kit. I designed this to be printed on a resin printer, however I think it should print well on a FDM printer as well. I have included a magnet adapter that will fit on the type of shaft you see in the last photo. I have also included the original Fusion 360 files so that you can modify the designs based on the motor that you have. The magnet and adapter piece need to be glued in place with a drop of CA or slip fit Loctite.
Printed the mounting plate flat on the photon build plate, added supports to the magnet adapter because it was best printed at an angle off the build plate. 0,05mm layers.