I recently purchased an IBM Selectric II typewriter off Trademe.
Cover off, tinkering time.
It really is a marvel of engineering. It's completely mechanical, besides a single electric motor supplying torque. In other words, you could hook up a hand-crank or foot pedal, and the whole thing would work exactly the same. And for something mechanical, it manages to do quite a lot. You can set and clear an unlimited number of tab stops, correct text without taking your hands off the keyboard, do super- and sub-script, adjust the striking distance and impression strength, etc. It's just amazing to see it in operation.
In fact, it's quite easily the most complex piece of mechanical equiptment I've ever seen. And, after my tinkering, it's in perfect working condition - not a single problem with it - which is fantastic for something this intricate and this old (it was built in the mid to late 1970s). If you open up a typewriter only a few years more recent, all you'll find is some dusty circuit boards and stepper motors. The Selectric, on the other hand, is filled with crank shafts, gears, bars, hooks, cams and springs.
The platen is a full 15", meaning it can accomodate A3 easily. In fact, it can accomodate something 25% wider than A3, as shown here.
It's a "golf-ball" typewriter, meaning it has a single, round type element that is rotated to the correct position and then pressed against the page. Why? Well, with a single typing element it's impossible to have more than one piece of type in the same place at the same time: using a golf-ball completely eliminates overstriking and typebar clashing.
I've spent the last couple of days tinkering around with it, and fixed a lot of minor problems. Quite a few of them were to do with the angle of the margin rail - if it's slightly out, you end up with all sorts of problems, from the carriage getting stuck to the right of the right margin, to the right margin warning bell ringing only a couple of characters before the keyboard lockout (annoying).
It's sky blue. Not that you can tell by these photos.
But now, it's my favourite piece of hardware, even ahead of my beloved IBM Model M. They share a very similar key weight, which is very nice.