Summary This is a filament spool holder with optical speed pick-up that can rest on any flat surface or be attached to the back of a Flashforge Creator Pro with the included back plate adapter. I wanted an upgrade to hold more than the spools that came with my creator pro, and took it a little far. :) As much as possible I have used common parts available at most hardware stores. Source code for the spool speed detection is in progress. Instructions These .STL's are for the left hand side, I need to mirror this setup and create the right side. The speed sensor code is still a work in progress, it will be arduino based and hope to have it also interface with sailfish for jam/issue detection. At the very least it will text/email/call/page/send a pigeon, something when it senses and issue. The Speed sensor it self is based off this sensor Or Alternatively The bearings are from Lowes You will also need some rubber o-rings to place in the bearing so the spool has traction. All Thread1/4-20 for the bearing shafts.