These were fun to make, and the kids love to use them. I had no idea how to do a mitered corner back when I made these, so that's why the corners are odd.
I used a piece of chalk cloth about the size of a place mat. Then I cut some woven fabric for the backing, binding, and wrap around part. I put iron on stabilizer on the woven fabric. The black 1/4" elastic is for holding 4 pieces of chalk. The closure wraps around a loosely rolled place mat and keeps it closed with hook and loop. They are great for keeping the kids entertained before dinner comes at a restaurant, or they like to use them at home or Grandma's house since they are so portable.