The Manhattan Project quickly began to design and build a practical atom bomb. It is interesting that during the conceptual design stage, Edward Teller was already thinking of how to make the much more powerful Hydrogen bombs. His ideas were set aside for the time being, to pursue the conceptually much simpler fission bombs. The first bomb to be built was a plutonium implosion device, and was referred to as the "Gadget". The gadget is pictured above, prior to testing.