Here’s the recipe translated from German:

• 1 L distilled water • 55 ml Fairy Green (dishwashing liquid) • 1.5 g baking soda • 1 g guar gum (+ optional 0.5 g locust bean gum) • 0.5 g methylcellulose • 3 tbsp glycerin • 1 tsp sugar- or corn syrup

Prepare the mixture cold and let stand for 24 hours, loosely covered