Frau Melitta Bentz couldn't stand seeing coffee grounds in her friends' teeth at a coffee klatch one day so she invented the coffee filter and went on to make millions with her Melitta Corporation. Divorced mother Bette Nesmith was unaccustomed to using an electric typewriter that was unforgiving of errors. A freelance artist, she brought a tiny bottle of white tempera paint the next day and created Liquid Paper.