Cut off and discard the lower two thirds of the soda bottle
With a hole punch, make two holes in the bottle, as shown
Make a chain of the rubber bands and thread them from the
top of the bottle, into the first hole, out of the second hole and up to the
top again, as shown above
Inflate a balloon inside the bottle, as shown above, and
screw the top onto the bottle to hold the air inside the balloon
Using tape, attach the two batteries together. These
are used just for weight, so the polarity of the batteries does not matter
Use tape and the paperclip to make two hooks at one end of
the battery.
Tape the tack to the top of the battery
Hang the batteries from the rubber bands. Adjust things
so that the tack is located just below the balloon.
