Found this gem on Crafts on Sea
You will need:
Paint – we used pink, white, yellow and a sparkly red
A felt tip pen
Painting with cotton wool
Firstly I drew the shape of a heart onto the card, I really recommend using card rather than paper because it holds a lot of paint a lot easier. Preschoolers are not known for their delicate ways with paint so this stops the paper falling apart when it gets too wet.
We put the different coloured paints onto an old plastic plate, using a plate rather than pots allows kids to mix the colours together and is easier for dipping the paints in....