The early series focused on inventions related to electricity, automobiles, aviation, and early radio technology. These inventions were grounded in the scientific advancements of the early 20th century and reflected the excitement surrounding new forms of transportation, communication, and energy.

The later series embraced the advancements of the Atomic Age and the Space Race, featuring inventions related to nuclear power, rocketry, and space travel. Tom's creations became more futuristic and reflected the growing fascination with exploring new frontiers of science and technology.

The most recent series incorporated elements of the Computer Age and advancements in biotechnology, featuring inventions related to robotics, artificial intelligence, and genetic engineering. These series reflected the growing importance of computers and information technology in shaping the world.