i used a 200L can sheet, (for the second attempt) and painted with high temp paint, the SS ring was ok, but had some issues (that i didn't liked) with the "seal" between the upper and lower kettles....
so i used a 200L big can, and used the rolled ribs that the can has every third (on length)... turned out much better,
what i didn't liked (for the first ring, that is the same measurements than the original pizza) is that the heat could escape very easily from the oven... thats why i changed everything for the another one