I saw this project in the Disney's Family Fun, kids magazine and made it with my son.
We simplified it by just using painters tape instead of a stencil cut from contact paper and it came out so neat I made one for myself using the puffy foam stickers.
It is messy so prepare your area and yourself and child with covers. We wore plastic bags with holes cut for the arms and head and did it on the porch with more plastic and card board to protect the wood. You can also clean it up with soap and water.
List of supplies.....
small spray bottle
painters tape or puffy stickers
white cotton shirt
Cardboard( to prevent bleed through)
Plastic to protect surfaces and yourself.
First place cardboard into shirt to prevent bleed through and then using painters tape or stickers make a fun design, remember this is where the paint will not be.
Let this dry a bit before you remove the tape and then hang it to dry. Then follow the paints directions for setting the paint. If you want to do the other side go for it!
Enjoy and get messy!