I'm sure you could engineer a case that pierces the right parts of the phone such that it is effectively a [self-?]destruct button. The biggest issue with this

I'm sure you could engineer a case that pierces the right parts of the phone such that it is effectively a [self-?]destruct button. The biggest issue with this of course is that if you have a legitimate threat profile that requires you to be able to quickly destroy your iPhone, you're not going to have an iPhone in the first place.