Mixing the casting compound
Take about 8 tablespoons of concrete for each mold and mix it carefully with water until you have an even, creamy mixture.
Make sure to fill the mixture only to just under 5 mm below the edge of the mold to make it easier to remove the castings later.
Tap the filled molds gently on the surface a few times. This will allow air bubbles to rise to the surface and give you a more even result.