E is for Experiment!
1 lb. box of cornstarch
1 & 1/2 cups water
Mix all the constarch and water together in a bowl. If the mixture is really thick, add some more water. The mixture should be slightly runny.
Here is waht is really cool about Gak. When you poke the gak quicky, putting pressure on it, the Gak particles lock together and it acts like a solid. But when you poke at it slowly, this doesn't happen and the Gak still acts like a liquid.