So I've tried a thing called FR4, which is some variation of G10, a circuit board material. I've ordered a thin sheet, used a spare bed magnet to glue to it, and have been testing it with PETG.
I was unimpressed at reasonable 70 and 80 degrees temp, but 85 works a treat! If you know #printablok, these are tiny and fiddly, especially connectors on the 1st.
Keep in mind that I have 2 magnets between the heater and FR4, so need more temp to hold the prints. #3dPrinting #garolite

Had such a bad time trying to get my #Ender3v2 #3Dprinter to get a good first layer down, but I finally managed it through sheer #persistance (and a lot of cussing). Using #G10 (#garolite) on the bed which works really well when the settings are right.