Source: http://lifehacker.com/5634210/repurpose-a-chemistry-stand-for-dead-simple-3d-images
John Edgar Park, a photographer, tinkerer, and DIY enthusiast, shares his simple setup for capturing 3D images.
Fancy stereoscopic camera rigs have two lenses on a single camera body, or two bodies and set of mirrors and lenses to achieve that distance. Or, you can simply take a photo, slide your camera sideways and take another. This works for still subjects only.
I build this simple rig out of chemistry lab equipment. (Yes, it's the same bar stand and clamp set I used to build my Florence Siphon vacuum coffee brewer apparatus.) I pulled my focus and other settings, took a photo, slid it all about 2.5″ to the left and shot a second photo.
Check out his full guide for setup tips and additional information about combining your photos together to create a finished 3D image. While you're in the 3D mood, make sure to check out how to create 3D images that don't require colored glasses.