I covered a thick piece of plywood with one layer of cotton batting and then heavy cotton canvas. You don't want your block to be ironed on any spongy surface, it will distort if it sinks into the ironing cover. I put it on top of a wooden tv tray next to my machine. The table my machine is on, the tray can be pushed underneath the table when I'm not using it. The mini irons get very hot and too awkward for me to have next to the machine.