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Hello all!

I have had a lot of cr-10's and with that, lots of bowed glass. I bought 6 pieces of regular glass from my glass maker and yet again, they are all slightly bowed. So I had 2 questions.

How do I test which one is the flattest? (Preferably this could be fast)

Anyone reccomend a good place to get a replacement for cheap?

Second big question.
What is your favorite printer surface? I have tried pei, lokbuild, and ultrabase.