I've always been fascinated by the cool 3-d looking shapes you can make by tying string to some nails in a board (I believe they approximate parabolas?)
I had some colorful string around, so I decided to make some string art - here's how I did it, and what you'll need to make something similar!
*String (you can get colorful 'crochet thread' for cheap at WalMart - that's what I used)
*Small nails/tacks (I used 3/4" brads)
*Small mirror (optional)
Step 1: Concieve of It!
I spent a good while considering different designs - there are some very cool geometric patterns you can make with this technique. In the end, I decided that I wanted to make an animal of some sort. A fish seemed like it might lend itself well to being rendered in string, so I did some concept art you can see below. I decided to go for the more 3-d version at the top right.
You'll want to draw out your design at full size. You can use a simple photo editor to do so, but I found it easier to do by hand at first. Make sure to specify where each nail will go.
I used a circle of nails within which I could make lots of cool circular-star patterns for the eye, parabolas for the fins and tail, a grid that narrows towards the back for the scales, and then some basic line art for the rest of it. Try to think of cool ways to incorporate the different designs the string can make. I bet a dragon could come out awesome!
Since I did mine in pencil first, I decided to take a picture of it (shown below) and use mspaint to help me visualize what it would look like with all of the strings attached. Once you're satisfied with your drawing, count up your dots or at least ensure that you've got enough nails.