You will need:
at least 25 balloons
specific weather conditions (see below)
four-color package of food coloring
clothesline or a tree (optional)
This project may not be available in all parts of the country.
1. Wait for a night when the weather forecast is for 1) the temperature to remain below freezing for at least 36 hours, and 2) no precipitation for at least 36 hours.
2. Hold the mouth of a balloon open, and drop in nine drops of food coloring. The food coloring need not all be from the same bottle (i.e., it is permissible to put in six drops of blue and three drops of yellow, or two drops of red and seven drops of blue, so long as the total number of drops is equal to nine). The colors put into the balloon need not be the same as those put into previous balloons.
3. Set the balloon down carefully on a flat surface, so that the food coloring does not leak back out through the mouth of the balloon.
4. Repeat steps 2 and 3 for all balloons.
5. When all balloons contain food coloring, fill them from the tap with cold water and tie the mouths closed. Do not overfill the balloons.
5b. If you lose control of the balloon and the food coloring spills back out, rinse the inside of the balloon with clean water from the tap, and start over with nine new drops of food coloring.
6. Take the balloons outside. If you have a clothesline and clothespins, you may pin the balloons to the clothesline to hang upside down, but be careful that the balloons are securely fastened if you do so: otherwise, the weight of the water will pull the balloons loose, and they will break on the ground. (You may also lay the balloons on the ground, or a flat surface, leaving at least six inches of space between balloons. A smooth metal surface is preferable though not required.)
7. Check the balloons after four hours. If frozen, proceed to step 8. If they are not frozen, re-check them hourly until they are all frozen. The time necessary will depend on the air temperature, the size of the balloons, and the temperature of any objects or surfaces in contact with the balloons.
8. When all balloons are frozen solid, use the scissors to cut the rubber away from the ice inside the balloons. Discard the rubber.
9. Arrange the balloons as desired. The colors will display best if you place the colored ice "eggs" on something white in color. Snow is ideal, since it will remain cold, though white gravel will also work well in most circumstances.