Rigid boards of one kind or another are what most folks think of when they think "signage". Substrates vary in composition, thickness, weight, rigidity, durability and price, so the material we use for any particular product depends upon a number of factors. 

Happily for our clients, we have a wide variety of choices available to us through our network of suppliers.  We're never at a loss for at least a couple of solutions that will work.