Update: I updated the rollers due to problems with almost empty filament rolls; they aren't heavy enough and the friction just tops them off the holder.
The new rollers are based on bearing idea I saw in Thingiverse some time ago. I didn't find the thing, but modeled my own. Rolling just fine. The model has tolerance of 0.1mm. Use horizontal compensation. feed rate etc. to make them print properly.

Wanted to test some ideas and needed better, adjustable filament roller. Soo I tested my ideas by creating this filament roller.

The roller parts need some lubricant, I used PTFE spray and/or some silicon grease. Still they don't roll too well in this application so I might replace them with something else. Doesn't seem to matter, filament rolls glide on them so it still works fine.

Highlights:

• only printed parts
• adjustable for different size spools

BOM:
4x axle.stl
4x washer.stl
4x nut.stl
4x roller.stl
4x foot.stl
1x big_nut.stl
1x frame_parts.stl
1x frame_nut.stl
1x shaft.stl

Assembly:

• slide the feet to the frame parts. They can be quite tight, so use file or knife to remove materila if needed.
• the rollers have their center printed as separate parts. Add some lubricant (PTFE spray) and pop them inside the rollers
• same goes to the frame_nut, it uses same mechanism
• install the long shaft using the big nut. Fasten it to the frame part that doesn't have the roller center
• the frame part with the nut can be threaded on the shaft, moving the frame
• each roller is to be fixed on the frame with axle, washer and nut. Washer should be in between the frame and roller