To do this, you need a tripod, a digital camera, and a photo-editing application (i use PaintShop Pro).
I took a picture of my scoot, and then took off that legshield, making sure the rest of the scoot didn't move. Then take a second picture. Take both pictures off the camera, and cut out the difference (front shield in this case). Copy/paste that from the complete picture to the one that's missing the part, and be sure to paste it into a new layer. Then, you can play with layer transparency to make the part show up more or less. It's a good way to show something in it's original context. Or, you can do it with your kids and make one of em appear like a ghost, whatever floats your boat
