Customs wouldn't bother. If your name comes up though as someone they "know", then they could turn it in to a Local PD to handle. They could do that even if your name isn't someone they know too. Or they could just through the shit into the trash. I would estimate though, that with about 85% certainty, that if Customs opened you pack(IF they did), and found 12 amps, that they WOULD just ditch the stuff. Probably wouldn't even get a Customs Letter imo.