Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:2193289.

Spool holder for sample or small quantity filaments that are loose (not on a spool).

Designed to fit into a 3" (I.D.) cardboard tube. This size of tube is very common (in the US)... most rolls of tape (packing tape, masking tape, blue painters tape) are usually on a 3" (I.D.) cardboard core. As well as packaging tubes are commonly 3" (I.D.).

The outermost diameter of this print is 6" across (just fyi)

The center is sized to fit a common 608 "skate" bearing or can be left as-is.