Spool Adapter for GiantArm Clear PLA or any 75mm spool

I have an Elegoo Neptune3 Pro which has a tubular spool holder with just an edge lip to prevent the reel falling off. Works fine, until I bought some GiantArm Clear PLA because I wanted a PLA that's as clear as possible and the GiantArm one is pretty clear - you get some frosting due to the layer lines in the print but it's not cloudy.

I quickly noticed that my printer had started making awful creaking and screeching sounds when using this filament. The sound seemed to be coming from the direct-feed extruder assembly. I tried helping it by pulling some filament through the runout sensor and that got rid of the sound until the extruder caught up and needed to take some straight from the reel, then SCREEEEEEEEEECH!

I don't think the feeder is slipping at all, as there's no underextrusion, it just sounds like the feeder is struggling to pull filament off the reel.

Part of the problem is that the spool has a very large hole - 75mm. In the end I worked out that the force needed to pull filament off a spool with that size hole is significantly greater than if the spool hole is smaller. I couldn't find an adapter that was exactly the size I wanted so I made this one from scratch. Also the spool material of the GiantArm spools seems slightly more “grippy” than the surface of printed PLA, so using an adapter also decreases friction due to that aspect.

I still got a fair bit of squeak from the feeder, but I think that's because this particular filament is quite unusual in that it's so shiny it's “squeaky clean” - if you rub two things together that are squeaky clean, surprise surprise you get a “squeak”, hahahaha! Anyway, it's a work-in-progress and I ended up designing an Ultra-Low-Friction Filament Guide which eliminated most of the problem and I've published it here https://www.printables.com/model/847922-ultra-low-friction-filament-guide-for-elegoo-neptu 

Hope this somewhat niche design helps someone else!

I found very slight difference in size between one side of the spool and the other, so I designed mine with a compromise size, and both sides needed a couple of dots of superglue just to make sure it stuck to the spool safely. I added 0.3mm to the diameter before uploading this STL. If you want it really tight then you might want to scale just XY upwards a tiny bit. 

Print settings aren't critical - I used 0.2mm layers, 0.4mm nozzle, 3 walls, 2 tops and bottoms, and 15% infill.