It should resemble a colorless to milky, shimmering volcano. There should be no cracks in the gelatin, but it's OK to proceed if one develops during unmolding. Place the peg board on top of the two bricks. Fill a syringe with red water. Remove air bubbles from the syringe by holding it upright and squirting out a small amount of water.
Air tends to fracture the gelatin.
Predict what will happen when red water is injected into the gelatin cast. Insert the syringe through a hole in the peg board into the center of the gelatin cast. Describe how the experimental results compare with your predictions. Refill and insert the syringe as many times as possible. Compare magma migration each time.