Tou could try something as an oven steel, like https://misen.com/products/oven-steel https://misen.com/products/oven-steel I bought a similar piece of 6 mm. st

Tou could try something as an oven steel, like https://misen.com/products/oven-steel https://misen.com/products/oven-steel I bought a similar piece of 6 mm. steel slab at an online shop (in NL, Misen doesn’t ship to here).