Velcro
George de Mestral is correctly credited with inventing Velcro -- but it took him over a decade to convince anyone it wasn't a joke.
In 1941, Swiss engineer George de Mestral came home from a walk in the Alps covered in cockleburs, the small spiky seed pods that stubbornly cling to fabric and dog fur alike. Instead of just picking them off, he put one under a microscope to see exactly how it grabbed on.
What he found was a field of tiny hooks that caught on the small loops of thread in his clothing. It took him roughly a decade of experimentation with weaving machines and synthetic fibers before he landed on a durable, mass-producible hook-and-loop fabric, patented in 1955 under the name Velcro, a blend of the French words velour and crochet.
Even after the patent, nobody wanted it. Fashion designers considered it cheap and unglamorous, and it took NASA's adoption of the fastener for zero-gravity equipment in the 1960s before Velcro shed its reputation as a novelty and became the default fastener it is today.
George de Mestral's Velcro is correctly credited to him, but the design was dismissed as a novelty for over a decade before NASA's use of it in space equipment made it commercially viable.