3d printed threads and snap connectors are nice, but M3 bolts and nuts are more robust and look dope. They also make the model easier todesign print, since you don’t have to worry about tolerances as much.
STEP/STL and instructions available here: www.printables.com/model/548770-master-spool
Master spool standard has mesurements the refill is supposed to fit in. The spool is printable on a 200x200 bed, that’s why it’s so popular. Every website I have seen, they state ckearly when compatible so idk.