Just finished doing this fun craft. I would definitely try it again. Some things that we discovered is that using one brand of crayons is better than several because they heat differently. RoseArt didn't work too well for melting, but crayola was a good brand to use, they heated fast and spread nice.
Also on these boards
The crayons are lined up along the edge and melted on a foam board using a heat gun. Specific heat is applied for the desired outcome of several defined drips. There is direct dripping from the crayon pieces that extends through the lower third of the board, with some drips extending all the way to the bottom. Wrappers are left on this piece to emphasized the melting of the crayons.
Crayon Art ---- I love the black background. On the source page, they hung this on the wall above a doorway. ((I went back to the website, and found they adhered the crayons to cardboard, and attached it to the canvas.. GREAT IDEA if you don't want the crayons hanging on your wall))