UPDATE. TPU lasts a lot longer than PETG because they can wear out after a while.
A similar design that you may want to consider... AbeFM Designed this one. https://www.thingiverse.com/thing:3152199
You can see this thing listed on PrusaPrinters.org as well. https://www.prusaprinters.org/prints/3151-mmu2s-tension-screw-retention-washer
Every time I loosen up the two Idler tension screws and open the MMU2s one or both of the screws and their springs would fall out. They would bounce around and play a mean game of hide and seek. So I made these little guys. Literally the smallest things I have ever 3D printed. They are small retention washers that will hold the screws in place when the MMU2 is open. They work great! I highly recommend them to everyone with an MMU2.
Any TPU or PETG
The washer model is .2 mm tall. So I strongly recommend you print using .2 mm resolution so it gets printed in one pass. Do not use .1 mm resolution because it won't have enough time to cool before the second layer gets printed.
I also suggest you use a flat print bed. Not one that is textured like the power coated steel sheets. The idea is that you want these washers to be very thin.
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