You have probably seen these all over Pinterest.
Same as the original art, we took it outside and began to heat things up with the blow dryer. Instead of letting it drip in one direction, we rotated the paper around as the crayons began to drip. Each time, it creates a unique creation. My kids thought it was so cool to watch the crayons melt and mix together. It was unexpected to them because I didn't tell them what we were doing before hand.
A few suggestions: Watch out with the blow dryer, it does get hot and so does the paper. Don't burn your fingers. And if you do it with children, have them stay clear of the heat and only handle their artwork once it has cooled a bit. Final suggestions, not the best craft on a windy day.