For blank shrinky dink material, you can find it at a local craft store or you can buy from Amazon.com.
You can buy all sorts of odd things like special shrinky dink markers and a special oven (that looks a bit like an easy bake oven). But I find pencil crayons, a Aluminum foil pie plate and my oven work just fine. Please don't use water soluble markers or wax crayons to color the shrinky dinks ... They don't work. Regular school pencil crayons do work just fine.
Note from a viewer:
"Another thing that works great for the Shrinky Dinks instead of the oven is a craft heat gun. I've used that and it works really good!"
Thanks for the tip Deb!