My very simple submission to the Makerbot filament challenge. This falls into the category of simple spool holder. It has been made to fit an open source filament spool that I had. And the diameter of the middle piece of this model is 35 mm. Hope you like it.How to print (quite simple): Part 1: Lay part flat with hole facing upwards. NOTE: May need to rotated 45 degrees on some square beds if it does not fit. Part 2: Needs a small amount of supports. But print standing up right for best finish. Hope you like it!