I have taken one of the old cardboard like table mats that fold up and used that in the same way. Sometimes you can find them in a thrift shop for about $1. I have glued batting to it and I can keep it under the bed in the spare room when I don't need it. I also have a design wall but I usually have several projects going at the same time so it is nice to have the backup. Good idea on your board. I had always seen them used for kids science projects but never thought of using them for quilting.