Introduction

A master spool is a spool designed to be reused (aka, that last spool you'll ever need). This is my take on that concept, designed to be printed on a single MK4 bed - although, being parametric (and hopefully, well behaved), any size can be generated.

These kinds of mini-spools are awesome for filament samples, for example, the 50g samples you can get from Atomic Filament (Made in the USA, with quality at the level of Prusament). Samples are great if you need only small portions of more exotic colors or materials - less waste (and I can tell myself I don't have a problem).

I wanted the core of the spool to be swap-able, so I opted to use heat-insets.

BOM (Bill of Material)

• 6 x M3 flat-head, countersunk screws between 5mm and 8mm. I used Torx stainless-steel 6mm screws from Aliexpress.
• 6 x M3 heat-set inserts with a max length of 5.7mm. I used standard sized inserts from CNC Kitchen (which I believe were made in Germany). You can purchase them from Prusa or from Printed Solid (in the USA).

Print Settings

I used IEMAI PETG-CF, which, after calibration, has absolutely no stringing, excellent layer adhesion, and virtually no warping on the Prusa satin sheet (although, diameter consistency is questionable). With this IEMAI, I use a nozzle temperature of 235c (using a diamond nozzle from ChampionX) and a bed temperature of 90c (85c for the first layer). Retraction set to 0.8mm (default speed), with “Wipe while retracting” enabled.