Here's what I used for this shirt (really you can use just about anything for the stencil):
- Sharp hobby knife
- Sheets of cardboard (flattened cardboard boxes work well)
- Spray bottle (got mine from the Dollar Store, though they charged $1.67, what a crock!)
- Bleach (again Dollar Dollar, but was more. Seriously guys, change your name)
- A fun shape (any object will work so long as its silhouette is easily recognizable)
- Plain t-shirts
Mix the bleach and water 50/50, you're going to need a bit so I'd recommend a minimum of 250ml (1 cup) of each. Now is a good time to wash your shirts to get the shrinking out of the way.