Keep in mind, the only thing you need to "kill" is your hard drive (hdd) or solid state drive (ssd). Very easy to do in both cases.
For hdd, drill a couple holes in the platters. They are soft, and any really cheap drill and drill bit will work. You can drill though the enclosure - no need to disassemble. See pic:
For ssd, melt the chips with a lighter or propane torch. If you have a 2.5" ssd, take the pcb out of the enclosure first. Also, you can just crush the chips in a vice or even with a large pliers. Remember, you want to destroy the flash chips. The controller and dram don't matter. See pic:
I don't take any responsibility for that but on HDD's you just need to open it and just hit it with a hammer.
When it comes to SSD's, I once heard that people would get a used/cheap microwave and put the SSD's in there for one minute. But I would rather not do this in my apartment :P
I personally have my own method to completly destory an SSD but it's very dangerous. I use chemicals which makes the PCB and the chips disappear in 3min
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and hey, if you are interested in distributing something, I can let you know that I'm currently working on something that does something similar like this pendrive.
The only thing is that I have a small group who's contributing to this project and the final product will be distributed somewhat for free.
It's free if you download the .bin file and use Etcher to flash the file to an USB 3.0 pendrive.
However, you have a second option, where you pay like 8euro/10pound for a SanDisk pendrive that will have this system pre-loaded and ready to boot (EU Only). Of course I have to mention that this is an non-profit project. The money would go for the pendrive and for shipping.
The only problem is that it's crashing most of the time if you try to erase a SSD with it :P
When the product/tool launches, you could theoretically sell this product in your country as long as you keep it non-profit.
But yeah, we still have some issues that we try to solve and we don't want to launch a broken product or a product that will connect/ping to some remote servers to download some potential update files.