There was some other technology IBM produced that was fascinating. The 028 and 129 card punches had a thing in them called a code plate and an elephants trunk for printing characters. The code plate had a large array of tiny square protrusions, where with a certain x and y displacement, and then displacing in the z direction would hit specific protrusions on the elephant's trunk to print a character (5 x 7 dot matrix). I never worked out how these code plates were made. The lynx belt printer was also one of their achievements.
Another fascinating device were the early Winchester hard disks. One I worked on could be as big as 5.1MB in the System/32, but it took two men to lift it. They cost today's equivalent of about $200,000. Let's not forget the 5225 "washing machine" printer. Very high speed dot matrix printer, that had 8 heads firing off at once, with massive transistors driving high current to the wires. Ceramic substrates were common on all this equipment. You will find them on any aluminium covered IBM chip - just peel the cover off and a jelly covered the chips (not an oil).
There were a lot of innovations IBM had that were not used elsewhere, possibly due to patents. I was fortunate to have worked these and a lot more in my first job at IBM.
By the way, the first TCM's around 1980 were about $25K, so in today's money, about $250K. And that was the IBM INTERNAL price as I recall. You would not want to have had one replaced and not be covered by maintenance contract.