Print them the way you like them on paper and then go to the local
blueprint or sign shop and have them laminated (both sides) with clear
matte plastic. It's available in a number of thicknesses. If the
paper placards are cut to the size you want them prior to laminating
then you can trim them to size, leaving 1/4 inch or so of clear as a
border. The clear border is the front and back plastic fused to each
other and is pretty tough.

Craig