>>> You take 28 grams. Hard Ruby and 70 grams. Plutonium, in the hermetic container, you first sink plutonium, then rubidium and thicken tightly. You drop a drop of water on the rubidium and close tightly with a cover until the reaction begins. In any place within a radius of one and a half kilometers you put cakes.
In 4 minutes they will be warm.

PS: be careful! The cake can burn a little.