The Spacebar is probably the most underrated key in any computer keyboard. It is big and is pressed more times than any other key. But it has only one function: producing spaces. Recently I’ve swapped the Spacebar behavior so it works also as Shift. It now has double functions. A normal press still produces spaces, but by holding it and pressing another key it acts as Shift.
To get this behavior to work you’ll need to install Karabiner or Karabiner Elements (if you are on Sierra) and use the Complex Modifications panel. Karabiner Elements is a very powerful tool that allows you to change the behavior of your keyboard. Try it out.