Great minds think alike. I have been using one for several weeks.
Also, it's a good idea to give it a coat of rubber cement (let it dry thoroughly). This will help to keep your cutting mat from sliding around on it. I don't mean glue down the mat - it's not necessary, and you may want to use the mat now and then without it.
I love the thing. It's a lot bigger than the ready-made rotating mats.