1. Tomato sliced to expose seeds.
2. Scoop out seeds (plastic spoon works well). Transfer seeds and attached pulp to a disposable tall plastic cup.
3. Fill with tap water and stir to mix seeds with water. Let seeds settle to bottom and carefully pour off debris until mostly seeds remain. Repeat 3 times.
4. Place plastic cup with seeds & water in warm place. A garage is ideal. Keep in garage until mold covers top of water.