In 1959, Bill Smith was an apprentice learning how to build the wooden patterns that foundries use to crank out everything from cast-iron cornbread skillets to the steel wheels on U.S. Army tanks.

Men poured molten metal into sand casts at Waterville Iron Works — which was perched on the banks of the Kennebec River — in the 1800s and early 1900s. They manufactured gears, parts for stoves, plows ...