As a teenager in the 80s built a MAA723 (LM723 in the West) regulated, variable, 2-35V, 1A, blah, blah, blah, power supply (used Tesla KD503 as power transistor, the 2N3055s we were getting were considered mediocre). No need to mention how proud I was, but... there is so much room in the box. I wind another transhormer and stick another channel in. Wow, I got a two channel PSU just like those in the brochures, with 70V when in series and all... Hmm, can I get 2A when in parallel?
Nope, you get a cracked chip (literally, the chip cracked and blue smoke came out, so that's my visual when someone says "the magic smoke came out"). My heart still aches...