iMac uses a Typewriter as a Keyboard
Yes, hooked up to that iMac is a real typewriter, and yes, it actually works as a USB keyboard. This is the product of a rather ambitious hack, here’s how it works:
Under the hood of every typewriter is a springloaded crossbar that runs underneath all the keys. When a key is struck, part of that key pushes on the crossbar, and this causes the carriage to advance, the ink roll to move, and so on. We are going to repurpose this crossbar as a place to mount an array of metal contacts, which are attached to a long, narrow circuit board. This Sensor Board is wired up to the Interface Board, an Arduino clone that talks to the computer over USB.
A fair amount of supplies are needed, but Instructables claims it is “surprisingly easy to implement” if you have a weekend to devote to it. You can check out the guide on Instructables to build your own.
Thanks for sending this in Evan!