This simple model is for the Snapmaker U1 to use a plastic spool on the side roller wheels that were designed for cardboard rolls not plastic.

Outside diameter of the bobbin is 61mm, outside ring is 95mm  

This should accommodate most plastic spools on the market.  It is not designed to fit perfectly inside a plastic spool but rather have slop room as not all my spools are the same diameter.  Spool can be placed either direction, I use it with the brim towards the printer, brim design seems a tad stronger overall.

Edges of the bobbin have a round type radius to them to push the roll away from both edges keeping it from rubbing.  Upon actual use for a couple prints I noticed that the roll does allow the spool holder on the printer to actually rotate as well so the spool isn't dragging across the plastic wearing it out.

When you are done simply slide off the roller and change material out as normal.

Print time is about 1 hour per adapter using above profile.  I print production type parts using a 0.6mm so your runtimes will increase using a 0.4mm.

** Please update your printed pics here, we would love to see them.  I will be uploading pictures in use.

MODEL DIFFERENCES

(3) models are available.  Solid, Cutout, Minimalistic

Solid is just that, solid (55.29 grams of material)

Cutout shaves 26% material use but adds about 2% additional runtime. (42.71 grams of material)

Minimalistic shaves 39% material over solid model use but adds about 2% additional runtime. (35.28 grams of material)