Hex Refill Spool

This is a remix of DasFilament's Little Masterspool that fixes some issues I had with it:

- Outer ring prevents the spool snagging on nearby objects
- Inner ring and hex grid makes it less likely that filament will shift around
- Adds more holes to insert the filament end into
- Makes the whole thing more sideways stable
- Prevents the filament from snagging on the rods

On the downside, it's more difficult to fasten the inner filament that keeps the parts from separating when used, it only barely fits on a Prusa MK3S, and it increases the total filament usage to about 100g.

I include the OpenSCAD file for anyone who wants to fiddle more with it. Requires the original STL files from DasFilament.

This is a first version, future improvements could be
- Add sign
- Round edges
- Use triangles instead of hex to allow filament end holes to avoid the walls

The white spool shown is an early version where the hex and inner ring didn't go all the way through on the peg part