Materials Needed:

3/4" (I.D.) PVC pipe, cut to 18" length
~.5 L (16.9) Plastic bottle w/ cap
1 Hex head cap screw, 1/4" diameter, 3" length, 1" of threads
2 Washers and nuts for the cap screw
Liquid Nitrogen
Bucket of room temperature water

Approximate Building Materials Cost (not including liquid N2):

$2.50

Tools Needed:

Saw
Drill press or power drill with various drill bits
Vise
Pliers

Assembly Instructions:

1. Cut the pipe to 18".
2. Drill a hole slightly larger than the cap screw 1" in from one end of the PVC pipe.
3. Drill a 1/4" hole through the center of the bottle cap.
4. Pull the cap screw through the hole in the pipe with washers on both sides of the pipe. Thread one of the nuts to the end of the threads on the cap screw. Twist the cap up onto the threads so that it sits against the nut. Tighten the second nut under the cap to fasten the cap between the two nuts.
5. Cut 2 tabs into the bottle as shown, so that the exiting vapor causes the bottle to turn counter-clockwise, or into the cap threads.
6. Fill with liquid N2, attach bottle to cap tightly, dunk in water, and enjoy!