I use something from Lowe's called "hardboard", which I think is like masonite. It makes excellent stable jigs that you can write on too, so you can keep records of settings or times or whatever. I usually engrave the settings and printer name right on the jig, plus add line designators (A,B,C, etc. plus 1,2,3,etc). You can buy large sheets and they cut it for you the size of your table, so it's easy to keep some on hand.