A couple of weeks ago, the kids were all asking to use the hot glue gun. Of course, the materials and equipment in the room are theirs to use so I said, "Sure." When I checked in on them, they were not gluing anything. Apparently, they were creating art from melting crayons against the hot tip of the gun. We have a bucket of crayons in the room and, holding the glue gun over paper, the kids pressed a crayon of a particular color against the hot tip and created art from the drippings.
One of the things that I like about this type of activity is that it was totally driven by students. They discovered it, they shared what they discovered and they began creating their art. I had nothing to do with it; I just provided the materials and watched the magic happen. To this day, kids are using the glue gun and crayons to put their own spin on crayon art. Below is a video of Ian creating with crayons.