The parts list for this experiment is as follows:
          >One used 20-oz plastic Coke bottle
          >Three large-diameter styrofoam cups
                (or something similar; see below)
          >A small kitchen sponge (1/2 inch thick)
          >A short length of nylon fishing line
                (thinner is better; 1-pound test is good)
          >A strong sewing needle
          >Four straight pins
          >One paper clip
          >Some paper towels

Step 1.  After rinsing out the Coke bottle, use a sharp knife to cut the bottle in two, about 1/2 inch above the bottom, as shown in the figure.  Poke a hole in the center of the bottle bottom using the sewing needle, and also poke four holes in the side of the bottle bottom.  Make a small round sponge to fit inside the bottle bottom, and hold the sponge in place by putting the four straight pins into the side holes you made (see figure).

Step 2.  Thread the fishing line into the sewing needle, and push the needle through the hole in the bottle bottom, and through the sponge.   Attach the fishing line to the bottle bottom with a piece of tape, and tie a knot in the other end to hold the paper clip.  When the Coke bottle is inverted and reassembled, the string should swing freely inside the bottle, as shown in the figure.

Step 3.  Place the inverted Coke bottle inside the three styrofoam cups, as shown, so that the bottom of the Coke label is at the same height as the top of the cups (see figure).  There should be about one inch of clear space between the sides of the Coke bottle and the top edge of the styrofoam cups.

You are now ready to make your own snow!

For more information, go to:

 www.its.caltech.edu/~atomic/snowcrystals/project/project.htm