the only time i've had to take care of this professionally, it was for a customer who'd bought a 286-25 (yes, back in those old days.)
i bought it from a "clone shop" in Fremont, a place i had found to be uber-reliable on previous purchases, plus willing to let me in the back to talk with the techs.
so i got that 286-25 back to the customer's office, they were subletting from an advertising agency in San Fran. the guy i worked for was wrote training manuals & stuff for companies like, well, automotive repair chains.
when the 286-25 crashed, i opened it up, and found that a disk was hanging by one loose screw.
as it turned out, the person that assembled it was fresh out of Heald or some other tech. school. and, they were a woman. just hadn't learned to tighten screws down yet when assembling a PC.
the guy i was working for went ballistic, threatened to sue the PC clone shop for $50K, and smashed fancy art glass stuff in his office while i sat in his secretary's chair and wondered if the whole mess was worth the $1000 they were paying me.
anyway, for that $1000 i ought not to have trusted the clone shop, i should have taken the cover off and checked stuff.
the guy i was working for demanded a free upgrade to a 386-33. in the process of returning the 286-25, i knew i needed to wipe the drives. so i used 81,000 copies of some image or WordPerfect file, i forget.
Like writing, "I will double-check my OEM provider's work even if I trust them completely", 81,000 times.
anyway, it sure was educational.
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i have a kiln that melts silver and gold quite effectively, so it'll do aluminum no problem.
so this is my nomination for data-protection - melt the drive down in a graphite crucible, then pour it into a bucket of water and see if it makes a cool-looking shape.