The printing plates can be made of anything that will go through the printing press and not damage the blankets or rollers.
This could include cardboard, textured paper, sand, tea leaves, rice, string, glue, gesso, tape the list is endless. Every item used in making the printing plate will hold a different amount of ink and therefore print a different tone. The more texture an item has the more ink it holds e.g. sand will print very dark, gesso a mid tone, whereas varnish will print with a very light tone. Once everything is securely glued to the printing plate it is sealed with acrylic varnish or shellac to make it more durable. The plate can be printed intaglio or relief or both.