All Other Mechanical Inventions

This group gathers mechanical engineering inventions that serve a genuinely different purpose from the other groups under this subcategory, including everyday fasteners such as the bolt, nail, screw and padlock, writing implements such as the fountain pen and ballpoint pen, recreational items such as the frisbee, trampoline and kaleidoscope, and standalone mechanisms such as the cash register, vending machine, Biblio-Mat, Pythagorean cup, Slinky and fishing reel. Their shared trait is not belonging to transportation, industrial machinery, timekeeping, tools, household use, weapons, printing or music, rather than any single function of their own.