I think that PETG can stick too hard to PEI unless you use glue - ironically - as a release agent.
I've had good results with the Lightyear 3D G10 (aka Garolite) bed on an X1C. Also seems to be available for Creality. Haven't used glue since for PLA, PLA-CF, PETG, PETG-CF, PET. Haven't tried ASA yet but I think I may have just found an excuse to crack open a spool.
Yup. You want to try machine tools as a hobby...makes this rabbithole look positively shallow!
Won't you then be back to a situation where if it fails or has problems, you're in trouble?