better mousetrap, (if one can) build a

build a better mousetrap

To invent something that improves upon an existing object or concept. You don't have to try so hard to build a better mousetrap—just design what interests you and see what happens.
See also: better, build, mousetrap
Farlex Dictionary of Idioms.

build a better mousetrap

to develop or invent something superior to a device that is widely used. (From the old saying, "If you build a better mousetrap, the world will beat a path to your door.") Harry thought he could build a better mousetrap, but everything he "invented" had already been thought of.
See also: better, build, mousetrap
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs.

better mousetrap, (if one can) build a

A minor but important improvement will bring fame and fortune. This idea came from a speech Ralph Waldo Emerson made in 1871 and quoted (or misquoted) by Mrs. Sarah S. B. Yule. Emerson allegedly said, “If a man can write a better book, preach a better sermon, or make a better mousetrap than his neighbor . . . the world will make a beaten path to his door.”
See also: better, build, one
The Dictionary of Clichés by Christine Ammer
See also:
  • build a better mousetrap
  • a better mousetrap
  • mousetrap
  • build
  • improve
  • improve (up)on (something)
  • improve on
  • didn't invent gunpowder
  • invent