I wasn't really happy with the built in spool holder on the M2, so I came up with this one. I think it works much better for the heavier spools. It is designed to hold the 5lb and 1kg spools from Ultimachine. It uses the existing hardware, and I kept the upper bearing holder from the original mount to keep the filament guide in place.This was modeled Rhino.Edit: Added a 1" diameter version (untested)Print, unbolt old, bolt on new. the original only uses three of the four bolts. When I put the new one on, I used the upper three since the bottom is in compression.I used 3 perimeters and 25% infill with PLA and it feels like I could jump up and down on it. You can probably get away with a lot less.