There are many versions and remixes of this type of roller. This one is remixed from: https://www.thingiverse.com/thing:2693565.

I wanted to be able to print certain filaments while the filament spool resides in the dryer / dehydrator; this can be handy for very hygroscopic filaments like nylon. This remix is such that the filament roller fits inside my filament dryer / dehydrator while still being able to handle 1kg spools.

The original design is modified such that the filament roller base plate is higher and has a recess to allow the base to fit the filament dryer tray. Also I made two changeable spool adapters: the 'normal' spool adapter fits most filament spools (with inner diameter of ~52 mm) that I have and the smaller version fits spools with an inner diameter of ~ 48 mm.

More information about the filament dryer / dehydrator and the related dryer tray extensions can be found here: https://www.thingiverse.com/thing:2865085

The filament feeder (angled) is this one: https://www.thingiverse.com/thing:2116535

Assembly is self explanatory. You will need:
3 bearings, type 626ZZ
1 bearing, type 608ZZ
3 bolts M6 x 20 mm (or longer will work too)
3 nuts M6

I used this https://www.thingiverse.com/thing:1928974 and my vise to insert the 608 bearing in the roller. Make sure the bearing is flush at the top of the hole of the filament roller base plate.