Here is a fun one to do with kids:
1.  Glue crayons to a sturdy art board.
2.  Use a hair dryer to melt the crayons.

MY TIPS:

• Use Crayola crayons.  I tried a generic brand & the colours never ran.
• I used regular school glue to attach the crayons because I was worried that if I used a glue gun it might melt from the heat of the hair dryer.
• Fair warning: Use newspaper or an old sheet to protect not only the surface underneath where you are working on but also the area behind the artwork because the wax tends to blow around a bit.
• Be patient.  It takes a while for the crayons to start melting but once they do, the magic happens quickly.
• The closer you hold the dryer to the drips, the more the colours will blend into each other creating a pretty effect.

BONUS TIP:
Uh-oh…How do I get wax out of my carpet?
I found this remedy on the internet & it worked like a charm.
Place a brown paper grocery bag over the spill with the printed side facing up so that the printing won’t transfer to your rug.  The paper acts as a blotter & will soak up the wax.  Use an iron on the lowest setting so you don’t burn your rug.  Iron the paper until it has soaked up all the wax.