"Assuming" I know what you are asking is a bit wrong at this moment. So here's a couple ideas/questions. If the customer requires them to be damaged to safeguard the information then do that(as others have stated).
If after the drives have been sufficiently damaged you could remove any outside case and save them up and ship them with other high grade material to the buyer of your choice. I highly recommend you use one of the members who advertise on the forum, read the feed back in their threads.
If all the customer wants is to safeguard the information and say doing a DOD type wipe on them is good enough then perhaps you can re-sell them as used on
eBay.
From you stated questions I am uncertain what exactly you have in mind. Mike.
PS Physical destruction is a good method of safeguarding the information on the drives. Mike
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