I recently tried hair chalking using blue, pink and purple and I really like how it turned out.
It was pretty easy to do as well.
All you need is soft pastels from any craft store such as Michael's
Then just choose your colour, wet your hair and rub the pastel over a twisted strand of hair.
Keep rubbing until the piece is completely covered
Wait for the hair to dry, then seal in the colour with a heated hair tool like a curling iron and flat iron.
Of course it only lasts unitl you wash it, brush it out or sleep.. haha