Waldo is a short story by Robert A. Heinlein originally published in Astounding Magazine in August 1942 under the pseudonym Anson MacDonald. It is available in the book Waldo & Magic, Inc., as well as other collections. This story is not related to the story "Magic, Inc." other than both stories being about magic in one form or another.
The essence of the story is the journey of a mechanical genius from his self-imposed exile from the rest of humanity to a more normal life, conquering the disease myasthenia gravis as well as his own contempt for humans in general. The key to this is that magic is loose in the world, but in a logical and scientific way.
Waldo Farthingwaite-Jones was born a weakling, unable even to lift his head up to drink or to hold a spoon. Far from destroying him, this channeled his intellect, and his family's money, into the development of the device patented as "Waldo F. Jones' Synchronous Reduplicating Pantograph". Wearing a glove and harness, Waldo could control a much more powerful mechanical hand simply by moving his hand and fingers. This and other technologies he develops make him a rich man, rich enough to build a home in space.
In the story, these devices became popularly known as "waldoes". In reference to this story, the real-life remote manipulators that were later developed also came to be called waldoes.