30mm Spool Holder

30mm filament spool holder, it should fit most spool types, except for the small Taulman spools (see the full list of spools I've used on [thrinter](http://thrinter.com/empty-spool-weights/)). Check the picture for how it's assembled. The extra "flex" part is optional, I printed it in NinjaFlex in vase mode (single 0.5mm outline), and use it to add some friction to the spool holder (it goes inside the tube, alongside the spacer). It seems to be working so far, but you can change the thickness