This is a lightweight parametric master spool design. The spool in the picture comes in at around 40g of plastic so it can be printed from left overs.

I designed this for spool-holders based on M8 rods like my own design: https://www.thingiverse.com/thing:4605888

However the inner hole can be scaled as well (within reason).

The design can be modified to your needs with a spreadsheet in FreeCAD, parameters include:

• the outer diameter of the wheels
• the inner diameter of the refill
• the inner diameter of the master-spool (default for 8mm rods)
• the width of the refill
• the width of the wheels

Print time for a complete spool is around 2 hours so way quicker than some of the more bulky master-spool designs.

Print two wheels and 4 spacers and click together. The straight side of the spacers should face outwards.