Hey so you can purchase a block at any art and crafts store.  Many times they are called "linoleum blocks" Look for them in the printmaking section, or ask about then up front.  I've found large ones (up to 4 feet) at an art supplies store.

Actually, that's not a linoleum block (it tends to be darker in color) that up there is a product called 'Easy-cut' and it's often sold to schools for use in art classes.  You can buy them in huge packs/kits from dickblick.com

you can use lino, the rubbery stuff that you can put on your kitchen floor.And you can glue something solid to the back of it. Thats what we use in our art class when were making prints.