breaking pins is easy enough to fix. I wouldn't suggest that option. You can:
a) open up the drives and break the platters inside
b) if they're working, use a program such as killdisk to do a low level format. This can take a while however it leaves you a working drive that is completely sanitized. Killdisk (not free) supports the same standards used by the DOD and even some stronger algorithms such as the gutmann algorithm!