My Multi-size Spool Tri-Adapter Roller Axle and Universal Spool Holder work for almost all of the spools I have... except flexible filament sample spools. So I made this adapter to accommodate those spools.
Added STEP (.stp) file for anyone who would like to modify this design. STEP files open in a variety of different CAD packages including AutoDesk's FREE Fusion 360.
Added "NutPlug" stl and stp (STEP). If assembled as designed uses a 3/8" coupling nut, tight friction fit.
Added "PVC Corner" stl, 123dx and stp (STEP) files. I admit the STEP file is a translated stl and not the best quality, as the original was designed in the now discontinued AutoDesk 123D Design. But if you have 123D Design, I also included that file.
Temperature settings will depend on material used and your own filament specific settings.
Should work off the bed. Throw in some R6 bearings and smoothly roll out your filament.
I use SolidEdge ST9 to design my parts (SolidWorks).