You will need

1 3/4 cup corn syrup
1/4 cup water
2 teaspoons red food coloring
8 to 10 drops blue food coloring
1/4 cup corn starch, sifted
Shaker jar or bottle that can be tightly sealed for shaking the formula

1. In shaker jar or bottle, mix corn syrup, water and food colorings. Shake very well.

2. Sift the corn starch so that it is very fine and add to the liquid mixture. Shake until completely mixed together.  If any lumps remain, let the jar sit for a few minutes. the lumps will rise to the top and can be skimmed off.

3. Store mixture in refrigerator. This will only last a couple of days, so make it just before you will be needing it.