I just bought a 5 pound reel of nylon trimmer line and need to rewind the filament onto smaller spools so that I can use it on my printer.

The spool I have made is very simple, using thick corrugated cardboard and bamboo take-away chopsticks, stuck together with a little wood glue. You can make it in no time using craft tools.

It is robust enough to hold up to 1kg of filament and used on the regular spool holder on an Ender 3 or similar printer.

I have included a dummy 1.stl file so that this can be published in Thingiverse.

Dimensions: (change to your preference)
Flange diameter 160mm
Inside diameter 40mm
Bamboo cage diameter 50mm
Height: 75mm

P.S. I have also made this with hardboard flanges. The product is more robust.