The Star-K gives this advice for kashering a glass top stove: https://www.star-k.org/articles/articles/kosher-appliances/2931/kashering-glass-corning-halogen-or-ceran-cooktops/
The sentence that I am asking about is: "it would be wise to place a metal disc, approximately 1/8 of an inch thick".
If anyone has tried cooking on a metal disc in this way, please tell me how it works, practically speaking. My concerns are: What type of metal disc? Where to buy such a disc? Does the disc mar mar or otherwise harm the stove top?