And while you're at it, why not make the laminated placemats two sided? Each side could be distinctly different from the other, so that you can alternate according to the season. For example, use a patterned wallpaper in happy greens for the summer, and a wallpaper in deep burgundy for the winter. Or make one side graphic with black-and-white, while the other side is soft and floral.
Where to get the wallpaper? Check end-of-the-roll supplies at decorating stores, or see what you find at our local thrift stores. Big-box chains and many paint stores also sell wallpaper by the roll. 17" x 14" is a good size for the final placemat. Why not give it a try?