you can use any fabric you like and just regular crayons like the crayola 64 pack.
i like to iron freezer paper to the back of the fabric it make it easier to work on.
when you're ready just put a protective piece on your ironing board, then the block, then another protective piece.
just press - do not iron back and forth.
this will make the crayon melt and look like paint and you've heat set it at the same time.