The IBM Selectric typewriter was a thing of utter beauty.
My dad was an engineer for Underwood; held several patents for them. Underwoods were made in Hartford; not far from Twain's Nook Farm; a few blocks from Royal Typewriter. Then, Olivetti bought out Underwood; the plant closed soon after that.
Especially the more refined Models II and III. The precise design and engineering to get a little plastic ball with raised letters on it to move so quickly and perfectly is still astonishing.