Found this on another forum. Sounds like an easy inexpensive way. . .
The design board is easy and fun to put together. Here’s how:
First, go to Lowe’s or another home store and purchase a piece of 1.5″ thick rigid foam insulation board. Where we live they only sell it in 4′ x 8′ sheets, and you can’t buy a half sheet, but at Lowe’s they’ll cut it in half for you, making 2 – 4′ x 4′ pieces. You can then make two of these design boards, or share the extra piece with a friend and cut your cost in half, like Cindy did. The foam board is about $20 with tax, so costs about $10 per design board.
Buy, or dig through your stash and find sufficient cheap white flannel to cover the board and wrap around the back. You can get plain white flannel pretty inexpensively at Joanne’s or maybe Wal-mart in 120″ width, or you can piece smaller leftover pieces together like Cindy did.
Press the flannel and then lay it out on the floor. Plop the foam board down on top of it. Wrap the flannel to the back on all four sides and fasten with brads, nails, staples, T-pins or whatever you have, stretching it slightly to make it tight across the front of the board.
And there you have it, your new design board!