I noticed after a few months that the filament going through the opening in the enclosure of my Snapmaker A350 was starting to wear away at the acrylic, which was a surprise. I tried a few different models and tried to modify them to fit this enclosure then just broke down and created my own model. Only the second time I have modeled anything whole cloth. Nut is a bit snug and had to wear it down a bit to get it all the way down to where I wanted it on the bolt. I printed it with PLA. 

I might have to adjust the size a bit… it makes a slight clicking noise as the filament pushes and pulls. Will update file if I come up with a better version.