About 15 years ago I made quite a bit of money recovering data from damaged HDDs using various low-tech means.

It started when I threw a very expensive (at the time) 1.5TB HDD. It had various things going on with it but I recall it wouldn't spin up and once I was able to get it to spin up, it wouldn't function for more than a few minutes before it would error out and the drive would become unrecognized by the PC.

I remember I made it spin up again entirely by accident. Figuring the drive was toast, I'd removed it and while fumbling with the cables it slipped out of my hand and landed on the hardwood floor. I hadn't noticed when I was holding the drive, but it felt like something was "stuck"[0] and after picking it up off the floor, it felt like the components were moving again. On a whim I plugged it back in and it worked.

The second problem, I knew, was thermal. The drive got incredibly hot very quickly. Being that it was a 1.5TB drive at a time when "that was big", I'd need the drive to be functional for hours to complete copying the data.

I had a dorm fridge in my office and debated putting it in one of my external cases and running a cable from there but knew that the moisture wouldn't play well. Because I kept very little in this fridge, it was filled with a few cans of soda, coffee creamer and about ten of those blue gel bags that people freeze/put in coolers in lieu of ice. I did this mainly because the fridge was really loud and keeping it stocked with anything made it run a lot less.

The upshot was that the size of these "bags" was just a little larger than a 3.5" HDD, if left out they maintained their temperature for hours[1]. I grabbed two, placed the drive on top, put two more on top of the drive and managed to image the whole thing.

It was so simple, I popped an ad on Craigslist and $200 "I'll get your data back or you don't pay." Out of 30-40 drives, there were less than 5 that were beyond help. About half were software issues, many of which were simple to resolve. Very few required a tool like photorec, but it did the job when needed[2]. The rest were handled with an extremely stable power supply, four gel bags and patience. Except for one of my own drives, I never popped screws and generally didn't resort to "applying physics and gravity" in hopes that if I couldn't recover anything, I'd at least give them a drive that was "no more damaged than when I received it" (they still signed a document covering me for any liability).

The whole experience made me realize how critical keeping "components other than the CPU" cool is. Every drive I've experienced hardware failures on[3] has had something heat-related coinciding. I remember one time I couldn't figure out which of the 8 drives was indicating failure; I saw one of the three fans in the drive cage wasn't spinning. I shut the server down, pulled out the fan and its 3-drive set, figured has to be the middle drive, swapped it and it started rebuilding the array on reboot. I guessed right. :)

[0] If you take a drive, lay it flat on a desk and spin it, you'll hear things move ... this one didn't.

[1] Provided it's just sitting on a wooden desk.

[2] There was one customer that I'll never forget and he was a reason I stopped doing this entirely. I told him I could recover photos/videos/specific file types from his drive but it will recovery everything it sees including files that may have been intentionally deleted. He said "Oh, no! Don't do that. I'll pick up my drive." I still wonder, to this day, what kinds of horrors I would have been in for (I rarely did more than a spot check on the data, anyway).

[3] I still have a pretty massive custom built storage server with an older LSI MegaRAID controller and a mess of SAS HDDs. For what it's used for, the speed is more than adequate the individual drive costs are substantially less (even taking into account SAS over SATA) and they outlive my SSDs.