I've got a GE ceramic cooktop where the burners are located in swappable modules. The problem that I am having is that each module has a metal "edge" around the glass less than 1 inch from the burner. This lifts a pot above the glass (on 3 sides) and makes it impossible to cook with.

And I can't remove the edging :(

What I'm thinking of doing is getting a square plate of metal (iron, steel, or aluminum) sized to fit nice and tight that will rise up about 1/8th (or less) of an inch. This would fit nice and snug and lift a pot above the edging while maintaining full contact with the glass surface.

Keeping it thin (maybe with some holes drilled through to reduce thermal mass) would help it cool quickly after the pot is removed.

You can't use diffusers of any kind on these tops, and that is what your plate would do.