Here is a very simple system with a number of advantages:
No gluing is necessary for assembly; parts snap or push together.
The Reel Arms allow two 8 inch reels to hang from a side or back of Thing-O-Matic or, for color freaks, on all three sides at once! That's six reels!
Filament won't easily spill off the reels and, if it does, it's trapped inside the arms and readily reloads.
The Filament Guide Arm can be positioned facing in or out of the frame, and the Filament Guide Tip on top of it swivels. I like to use it as shown, which gives the filament a very smooth path. Friction is not a problem; filament pulls off the reel with virtually no effort, and the reel turns on the rod very freely.
All parts clip onto the frame of the Thing-O-Matic and need no fasteners.
The whole thing sets up and takes down in seconds and stores in very little space.
It includes a Filament Clip (derived from thingiverse.com/thing:12516) to hold an idle filament to the reel.