I picked up a piece of 41cm x 35cm x 3mm float glass at the local glass shop. It weighs in at a hefty 1029grams. I’m printing a 300x300mm square picture frame just as a test of the large surface area. The glass does sag a bit in the center but that can be easily remedied with some supports underneath. So far it doesn’t seem to effect the print.
I think I’ll work on a system to make these print beds easier to interchange. I’d like to be able to put the smaller bed back on there when I need heat on the bed.