I needed somthing to protect my wedding ring from rubbing on the chain I wear it on. I wanted to protect both engraving inside the ring and the ring itself from damage.  I talked to a jeweler that said it wouldn't be an issue for the ring but I may lose the engraving. 

This file is for a size 10 comfort fit ring so this is more of an idea I'm putting out for ppl with a similar issue.  I used PETG for its durability, but PLA should work fine.  I've been using this for a couple months now and it works and I haven't had any issues with it.