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). 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 or size to control the amount of friction. Without it there isn't enough friction to prevent some filaments from unwinding.

Parts:

2 - 608 Skate Bearings*

1 - M5x65 Screw

2 - M5x8 Button Socket Cap Screws

1 - M5 Locknut

2 - T-nuts

Printer:

-- Eustathios

Filaments: (full list can be found on thrinter)

-- Atomic Filament Glow in the Dark PETG

-- 3D Solutech See Through Green ABS

-- Ninjaflex Neon/Glow in the Dark TPE

*affiliate link