Destroy a hard drive without proper equipment

Free Method: repeatedly throw the HDD against a sidewalk or concrete wall until it comes apart. Then continue to smash the platters (internal disks) until they are extremely damaged.

Side Note: This also provides some stress relief.

HDD are much more resistant than people think. And in one HDD the only thing that really matters are the platters inside it.

Can you make holes over your HD, drilling it? Make sure to drill from top to bottom. 3 holes and you're good. See that one HD have the platters somehow delimited in the top of it, and the connectors are on the other side. Make the holes in the marked positions.

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|          |
|  O       |
|       O  |
|   O      |
|          |
\          /
|          |
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¨¨¨   ¨¨¨¨
power data

Using a hammer and throwing it against the concrete floor are also good (let's say, 20% compared to make holes).

Running over with a car, even using rocks, is too little to damage the platters.

Fire is insuficient. (About 11 years ago, someone set fire on +- 20 computers in the prosecutor's office I worked, only in 1 computer we couldn't recover the HD data).

Platters are resistant. Someone said about fingerprints over it: once we opened one HDD, and with it running, we thrown some cigar ashes over it. It was still useable. Putting fingers over it: we still could recover information. It only stoped working when we used a screwdriver to create scratches over it.

Snipping off the pins will foil your average wannabe-MacGuyver. Some disks expose other circuitry, which you can further damage/destroy in a number of ways.

If the platters remain intact, the [insert-your-security-service-of-choice] will be able to read data off them. So you would need to significantly damage the platters or to wipe them them using a software tool. This seems to be beyond you, given your constraints, but given that you aren't concerned with security services, this shouldn't worry you.

I've never tried it, and won't vouch for any results, but baking the drive might be fun, as would freezing it. If you want to be thorough, alternately bake and freeze it! The expansion/contraction effects would cause plenty of damage I am sure.

You could also drop in the sea/in the middle of a lake, bury it in a forest, simply send it to me and I'll give it my kids - they seem to have knack of destroying all sorts of high-tech equipment that I own.