t-shirt or whatever, blank
image you want stamped, ( silhouettes are easiest)
blank stencil transparencies
stencil sponge or makeup wedge
Now you take your image, put it on your cutting surface, and then put your stencil transparency over the top. Tape them together so they won't move.
Then, take your x-acto knife, and cut out the black of your image. This is where your paint will go.
Put your cereal cardboard, or whatever, even another piece of paper inside your shirt so the paint won't leak through to the other side. Tape on your stencil where you want it to go.
Then take your stencil/ stamp sponge thing. It has a blunt top. Dip that in your fabric paint, and dab or stamp your stencil. I hope this makes sense... don't do strokes, as your stencil is only taped on, just stamp the paint directly on, or your image will be totally smudged.
Here is what it will look like.