I got a 12 X 18 X 1 1/5 piece of styrofoam, two pieces of stiff felt, sized to match. He drew a grid on both pieces of felt, 1" X 1", covered the edges of the block with duct tape, and then I pinned the felt on either side of the board. This way, I've got both sides to use - and can stand it up. The felt is then washable should it get dirty.
I also wanted to throw in this other picture. This is Gaisgeiel (Buddy G). He was helping me use the new blocking board today.
Maybe he thought if he sat on the squares it would help keep them blocked?