Summary

A design for adding a picavet (suspension system/gimble) to the pop bottle camera mounts at http://www.publiclaboratory.org/wiki/pet-bottle-rubber-band-rig

The design uses bicycle chain links as low-friction pulleys. You can use a M3 or 4/40 eye bolt instead

Weight with zip ties & 4 pulleys is 34grams (mark 5 design)

Instructions

As of 8/12, this design has not had a lot of field testing. The ideal arm length may be slightly shorter (or longer)

1) Find a laser cutter, a bicycle chain braker tool, and a length of scrap bike chain. Most shops will give you the chain for free.
2) Select the version you want to try. Version 5 is light and fine for holding the camera, but will break if you drag it on the ground. Version 7 attempts to make it slightly more rugged.
3) Cut the design. 6mm plywood seems to be the best for strength.
4) Remove every other pin from your length of chain. Each pulley is made from one set of links: there will be one pin, which holds the outside 2 plates, the inside 2 plates, and the roller.
5). Fold the plates so they all over lap, and keep the bottom roller between the inner plates. Your pulley is the part with the pin.
6) Thread a zip tie through the bottom hole, but don't zip it yet.
7) Squeeze the bottom of a pulley into the square hole towards the tip of the cross. All pulleys have the pins pointing the same way.
8) Zip tie the pulley to the picavet, using the notches and holes provided.
9) Push the center of the picavet over the threads of a 2 liter bottle. Not all bottles are the same size, so you might have to scrape off some wood or plastic.
10) Use a pin or knife to make a small hole under 2 opposite arms of the picavet.
11) Use string or fine copper wire (#24 picture wire works well) to thread through the 2 holes you just made in the bottle. Push the ends of the wire through the holes or notches in the picavet. This is how your camera stays attached to the kite, so make sure you've lashed things together well. Try not to obstruct the neck of the bottle too much, since your camera mount needs to pass through.
12) String the picavet using the instructions from http://www.kaper.us/basics/BASICS_picavet.html . Use one of the left over chain bushings as the central washer.

When you mount the camera, instead of mounting to a notch in the bottle, use one or more of the notches on the picavet. You can also knot the camera safety cord through one of the loops on the arm.

Thanks to Celaya for the clever pulley idea.

You can use the bottle cap to screw on this picavet. But this requires a hole in the cap for the camera mounting. You'd probably want to glue or tape the cap on.

Picavet for 2 liter bottle aerial photography