Perhaps two of the most commonly used inventions among all office supplies are Liquid Paper correction fluid and Post-Its. However, both of these inventions were not planned products and were in fact created by accident.

Bette Nesmith Graham was a high-school dropout whose dream career of becoming a painter had never taken off. Instead, she married at 19 and spent her days working as an executive secretary for the chairman of the board of Texas Bank & Trust. As a secretary, Nesmith often made mistakes while using electric typewriters. Frustrated by the constant errors, Nesmith decided to take a painter’s approach to the problem. Nesmith brought tempera water-based paint mixed in a kitchen blender to work and used a paintbrush to simply paint over her mistakes.

With her colleagues asking for bottles of “Mistake Out,” Nesmith began to realize the marketable potential of her invention. She started the Mistake Out Company in 1956 and patented her product with the name “Liquid Paper.” The company boomed and now produces Liquid Paper in various forms, including pens, bottles and tape.

In a similar way, Post-Its were never a planned creation. In 1968, at 3M, a multinational corporation that produces thousands of products, chemist Spencer F. Silver was given the task to design a strong adhesive. Instead he created a weaker adhesive that could stick to other objects but was easily removed. The invention was merely shelved as a failure until another 3M scientist, Arthur L. Fry, discovered its potential.

Fry spent his time outside of work in a church choir. One day, frustrated by markers that constantly fell out of his hymnal, Fry decided to coat his markers with Silver’s adhesive. It was an instant success and Fry immediately convinced 3M to distribute Post-Its nationwide.

Both Nesmith’s simple homemade creation and Silver’s supposed failure have become common office products used all over the world. These products have become two of the greatest “now why didn’t I think of that?” inventions.