When I wanted to spectacularize the gear art with my awesome future brother-in-law what I trying to do was have a large off center gear to focus the piece with trains of different colors trailing off the canvas.
My inspiration was a nebula.
My tool was a piece of cardboard.
Yeah, it didn't really work.
What I ended up was a grey sort of blotchy thing with washers that happened to be stuck to the canvas because the orange paint underneath wasn't exactly dry when I stuck them on.
I'm telling you all this because it explains why I decided to go the long route with my more successful art spasm. (ed- click the link to see the finished product)
See I've read that in watercolor you can use a wimpy variety of tape to select against which areas you don't want the paint to permeate. I figured that I would give it a try now with the crayon piece because someday I'd like to retry the already explained failure.
First I painted my canvas black so that the entire base would be one color. Then I found an acceptable 2D image of a gear* and printed out several sizes.
Because the tape I bought at hobby lobby was too sticky it ripped up the paper underneath as I was trying to detach it from the mold. I got around this by adding another layer perpendicular to the first. After all, the tape has to be able to come off the roll.
I cut out the gears and then arranged them the way I wanted on the canvas. I unpeeled the tape, then stuck them kinda sorta where I had painstakingly arranged them moments before.
Then after about a gazillion layers of white spray paint. I glued the crayons to the tape in the hopes that it would make the wax look like it was originating from the gears themselves.
Then I melted the crayons and voila! Instant art!
The tape didn't really work as well as I was hoping that it would, but I think that is mostly due to the fact that I was trying to go from black to white. If I had been going the other way I'm sure it would have performed much better.
*clip art *cough cough*