Please explain to me how to succesfully print PETG on a PEI build plate.

[dbhosttexas]

Okay so I think I've got a bead on it...

Wash and dry the PEI thoroughly, then get after it with ispropyl alcohol for a thorough wipe down to remove any remaining soap residue.
Apply purple glue stick to the build plate surface.
Default slicer settings for the Aquila X3 Max PETG profile in VoxelMaker.

It would seem once it gets past the first few bottom layers it will either stick and give me a successful print, or shoot off of the build plate like a slapstick comedian slipping on a banana peel. Not a whole lot of in between with this stuff.

With all of that being said, I have a successful print of the Raspberry Pi 5 Pimoroni NVME base case printed in transparent red PETG now.

Now if only Amazon would actually deliver my order my other colors of PETG are overdue...

[airscapes]

Glad you got a print done! Things like this are why the higher end printers cost more.. Tight tolerances, well built assemblies that do not change from how they are set, etc. Please know, that when everything is as it should be mechanically, PETG sticks to PEI like crazy glue on your thumb and index finger, no glue stick ever needed. There is also the possibility the filament is the issues, I do not recall what you are using other than it is from amazon. I have uses Overture which is fine and Esun which is fine and Matterhackers build and pro which are all fine. All PETG will absorbed moisture and will need to be dried in a dehydrator from time to time and even sometime fresh out of the manufactures vacuum bag. When it gets wet you will hear the water pop as it exits the nozzle and see bubbles and holes and uneven surfaces as the water boils out of the molten plastic.

[dbhosttexas]

The filament I am using is varied, but the one I got a successful print from is Polymaker PETG in transparent red. https://amzn.to/3WSt802 Pretty sure the issue is the build plate itself. Out of the box it is very and I mean VERY slick, almost oily feeling. PLA sticks but not super well. The Dawn dish soap was and acohol wipe down helped a lot. I suspect I am going to need to do this several times before it pretends to fully cooperate.I have a few spools of Firos PETG coming in, Red, Blue, Yellow, Dark Gray, Light Gray, and Black.I don't have a filament dryer yet. Not sure what to look for in those...For now, between prints, my filament gets vacuum bagged with silica dessicant packets, and the dessicant is not exposed to open air very long.

[airscapes]

I have one of these, just cut most of the trays so 2 rolls of filament can fit inside
https://www.amazon.com/presto-dehydr.../dp/b008h2oekk