Firstly, you need some toilet paper rolls, a large stamp pad, and foam stickers of your choice.
We'll go jungle themed
Just stick them on creating a picture horizontally...then roll in your big ol' stamp pad being sure all stickers are well coated, then roll away on paper. I am going to go create a bunch of these with my not so tots this afternoon!
EDIT TO ADD:
After playing with this craft WITH tots...we decided it was way more fun to place the rolls on a paint roller and roll the heck out of the paper on their IKEA easels! That's how we "roll"