I used several pieces of heavy plastic canvas. It can be left in when washing. I also found something the other day that I am going to use for stencils and templates and it would also be great for the purse bottoms. It is a package of flexible cutting mats from the kitchen department at Wal Mart. There were 3 to the package. It can be cut with scissors and is white. The sheets are 12 x 15 and only cost about $5.