Master Spool is an idea of a reusable spool. You just buy a so called ReFill filament and put it on your master spool. ReFill filament is a roll of filament with no spool. So you reuse the same master spool again and again.

And there are many beautiful and strong printable master spools on printables. But you will spend many filament to print them. I sliced some of them and they cost 150 to 200 grams.

I had few empty cardboard filament spools from OVERTURE and POLYMAKER. So I decided to convert those spools into cheap refillable master spools. So I designed this kit.

I converted only cardboard spools from Overture and Polymaker. I'm also going to check if this solution also fits plastic spools.

For each spool you will need 4 bolts and 8 thumbscrews. You will spend less than 20 grams of filament. Then you cut one wall of your spool with saw. then you drill 4 holes of 8 mm diameter on both walls of your spool.

Print instructions: 3 walls, 30% infill.

Good luck. And please share your experience.