Use hot glue to attach your crayons to the top of your board. You can do a particular order, particular color scheme, etc. (I mostly did this part, though they handed me the crayons)
Plug in your hairdryer and heat the crayons.
When the wax starts melting and spattering all over, move yourselves outside. :)
These crayons melted REALLY quick. I wonder if a brand such as Crayola would melt thicker/slower, etc. I also had the hair dryer on High. I would recommend low.
Once the crayons melt down as far as you'd like, turn off the heat and lie the board flat.
The girls thought that this was the coolest thing ever! We are going to trim the sides of the board some more and then hang it in their room.