Well, we've got a sturdy eighteen-inch wooden ruler...

As for material, gah, I have no clue. I was assuming I could just go to Michael's or AZ Art Supply and just, I dunno, pick some up...

Can I call you a little later? My mom's picking me up in about ten minutes so we can go get mats, and I'm beginning to realize I know even less than I thought I did. :D