Hardy, 36, said he is not leaving any stone unturbed to prepare for the part, reported Showbiz Spy.
"When I play a real person, I like to have bits of them. Since I can't take physical body parts and sever those, I try and grab as much 'kit' off them as possible," Hardy said.
He joked, "Then you can sell it on eBay."
The actor has also sparked rumours that he has secretly got hitched to his fiance Charlotte Riley.