If kids love stamping one thing, it's themselves.
I chose to use VersaMagic ink pads after experimenting with several different types. The VersaMagic stamped the cleanest on skin, washed off the easiest with only soap and water, and is non-toxic.
The instructions are as simple as it can be on this blog. Evenly ink up your stamp, gently press the stamp onto your skin, and allow to dry. Here my mom and I played with the butterfly and linked the heart chain stamp to make a bracelet!