Each board measures approximately 21 x 15 inches. They are super easy to make. I took 2 - 3 flattened shipping boxes and taped them together. Any sturdy cardboard would work. Then I padded them with either some thick cotton fabric or a couple of the vellux bead mats you can buy for $1.00 or less at the bead stores. This makes them nice and soft to rest your wrists on, and also gives a little cushion to stick your needle in. I'm sure there are lots of other options, but the vellux mats, and cotton fabric were what I had on hand. Then I bought a yard of vellux fabric from Jo Ann's fabric store, using my coupon so it cost me around $8.00. Out of that I was able to make a wrist rest, 3 boards, a cover for my camera, and still have enough for either another board or another wrist rest. I wrapped the fabric over the top and secured on the back with a staple gun.
Easy as that and I have a large bead mat to work on. I love it as it is easy to swap out projects without having to pack everything up. I just cover with a piece of scrap vellux cloth to protect from dust, set it on the shelf, and grab another project that I am working on. I purchased some great little ceramic dishes from the dollar store that are shallow and wide enough to be able to easily string my beads onto the needle.
Here are some pictures:
