I used the craft ink from my scrapbooking stash so not the kids stuff ... I versamarked (a clear ink) their hand and than stamped it with the craft ink and they stamped their hand on the shrink paper ... the versamark step was so that it would wash off better as it creates a bit of a barrier on the skin and than we also did water play to remove the remaining evidence as these were surprises for mom.
I imagine you could use the washable ink or tempera paint ~ it would just take longer to dry before you can 'bake it' and with the paint you risk it 'flaking' when baking but imagine that the heat would cure the washable ink hopefully ... I used the craft ink cause the shrink paper is expensive even when you use a 50% off coupon and did not want to experiment with it since they were 'gifts' verses just a creative art exploration ... I have some left over pieces now I should play around with different mediums with it with them to see!
The beads and clasps were from the Dollar store ... I tied the one end of the clasp on for the children and they 'beaded' the necklace with a little coaching on finding the middle for the 'big hand bead' so that it hung nicely for mom and when they were done I tied the other end of the clasp on for them cause that was fine motor work beyond their control
We also made 'key chains' for dad with the same concept.