Found this a while back, and honestly can't remember where. Hope you find it more useful than rocks, trees, magazines, and rotting carcasses.

How To: Make Ballistics Gel


1st Recipe
Take 1 part pectin powder (same store isle as gelatin)
then take 1 part gelatin powder
take 3 parts boiling water (double boiler reccomended)
Stirr untill disolved.
Add color if desired
A few drops of oil of wintergreen (from baking supply store) can be used as a preservative.

2nd Recipe
Start with 20 grams gelatin powder
add 12 cc distilled water
then mix with 100 cc glycerin (sometimes available at drugstores, first-aid isle)
Let the mixture soak for about 45 minutes, then heat to 140 degrees in a double boiler, and pour into ziplock bags and lay flat to cool. (add color if needed)
add oil of wintergreen works as a preservative here too.