I bought a sheet of perferated stainless from RS 590cm by 50 cm and cut it to a circle using tin snips and use that as my FB. Hold it off the bottom with stainless screws.
You could just get a sheet to go over the centre part that drops down. you can get it on ebay as well. and just put some screws in to keep it located at the centre hole
You could just get a sheet to go over the centre part that drops down. you can get it on ebay as well. and just put some screws in to keep it located at the centre hole