This is a wonderful way to add an interesting effect to your photos in-camera. This method seems to work best on point-and-shoot cameras, TLRs and camcorders. The kaleidoscope effect is a whole lot more subtle on SLRs, but interesting nevertheless.
Step 1: Materials
If you have some extra time, an empty film canister and a drill or a carpet knife, there's a slightly more advanced way to do this.
Step 2: The Easy Way
2. With the darker side facing in, arrange your strips in a triangle shape.
4. Hold up to your camera and head out to shoot.
If you don't feel like cutting or taping anything, you can simply fold your card either into a triangle or rectangle shape. This method allows you to change off between the triangle and rectangle shape by simply squeezing your hand.
Step 3: The "Hard" Way
2. Cut out a hole in the lid approximately the size of your camera lens. My Casio Exilim is the perfect size for just cutting along the inside border, but you may have to cut smaller or larger.
3. Slip in your kaleidoscope from the Easy method and slip over your lens. This allows for hands-free photography (unless you're using an SLR, in which case you'll still have to hold it.)