Make a water-based fluid for fog machines, or fog juice, by combining 1 quart of distilled water with 4 ounces of food-grade glycerin. Adjust the amount of glycerin for a more or less dense fog.
The basic recipe for homemade fog juice is 1 part distilled water to 4 parts high-quality glycerin. Multiply the recipe to produce as much fog juice as needed. For thicker, more dense fog, add more glycerin. For thinner fog that is easier to see through, use less glycerin. Add food coloring to the fog juice to make colored fog.
To make a homemade fog machine in which to use the fog juice, gather an empty two-liter soda bottle, a small aluminum pie tin, clear tape and a large candle with multiple wicks. If the candle isn't in a glass jar, find a jar that the candle fits inside.
Cut the top off of the empty two-liter soda bottle to make a funnel. Attach the funnel to the small aluminum pie tin with tape. Light the candle, and set the pie tin on top of the candle. Pour a few tablespoons of homemade fog juice into the pie tin. In a few seconds, fog begins to rise from the funnel.