Igus has tons of high quality plastic linear bearings and selection guides, lifetime calculator, etc. I’ve also got versions they didn’t have on their site by talking to a rep, like tighter tolerance for a specific bearing. Used them across many mechanism and products I’ve designed. Can get cheaper bearings elsewhere but without those resources so they tend to be my default.

I don't have any personal experience, but there are some interesting experiments being made by spanish guy with fully printed linear bearings and ptfe tubes. Maybe his work will give you some ideas on improving yours.

Update: found him - printabot