Soak the soy beans in water overnight (10-20 hours). Be sure to use enough water so the beans can double in size. Prepare the molds using one milk carton per mold (you can use cheese molds if you have them). Cut off one side of the carton, and punch numerous holes in the sides and bottom to allow liquid to escape. Reinforce the molds by using a pair of longs sticks (one on each side) holding them together with rubber bands on the ends. You should have one piece of cheesecloth per mold which should be big enough to fit squarely into the mold and cover the tofu inside.
The next day, pour out the water, and pulverize the beans in a blender using enough water to cover the beans (you will probably need to do this in four to five batches). Pour the bean mixture into a very large pot and add enough water to double the quantity of liquid. Bring the liquid to a low boil and lower the temperature, skimming off any foam that collects on the top. Boil for 20-30 min. stiring (and skimming) constently. While it is boiling, disolve the bittern (the leftover "stuff" that is formed when you extract salt from seawater) in a small quantity of water. Place a piece of cheesecloth in a colander, and pour the liquid through it into a large bowel. The liquid that passes through is called "soy milk" and will become the tofu. The solid material that remains in the cheesecloth is called "okara" and is useful for various Japanese dishes (recipes will come later). For each of the molds, fit the cheesecloth squarely into the corners. When the temperature of the soy milk cools to 70C (158F) pour in the bittern and stir genetly. When the tofu starts to separate from the water (almost immediately), pour the mixture into the molds and cover with cheesecloth. Next, place the plastic wrap covered newspapers on top of the tofu (it should fit squarely) and place weights on top to press out the liquid. After about 30 min., remove the tofu from the molds. This should be done under water in a large pot or tub. Store the tofu submerged in water.