I made just a few little changes from our original project so it was more manageable for a group. I only took a few pictures of the process this time (because I had nine giggly girls to manage ;) ), so you can check out my original post if you want more details.
To prepare, I bought 4-5 boxes of 64 Crayola crayons and separated them in bowls by color ~ reds, oranges, yellows, etc. I also had pieces of contact paper cut in squares for the shapes and stencils that they could use to make their initial, a heart or a star.
Because I didn't want all of the girls wielding their own glue guns to attach the crayons to the canvas, I had them use glue dots instead. The dots held just fine and held the crayons in place right away (without having to wait for regular liquid glue to dry). I'd still recommend a hot glue gun if you're making just one by yourself, but for kids, the glue dots are the way to go.
I also gave each girl the option to put a shape or initial on their canvas, or just use the crayons. All of them chose to put something on their canvas They cut out their own shapes after tracing onto the contact paper and then put them on the canvas.
Finally, because I had some problems the first time with the melted wax seeping under the contact paper, I used hot glue to seal around the edges of the stencil. I just ran a line of hot glue around the top and sides of the shape. You don't want the edges of the stencil to be raised or the melting crayon wax won't flow over it, so I held the tip of the glue gun right on the canvas so the glue line was as flush with the canvas as possible. (Hopefully I'm explaining this okay, I wanted to take a picture but things were just a little too hectic at the time.)
Here's all the fun they had during the process...