The 36-year-old actor portrays the 'Candle in the Wind' singer in forthcoming biopic 'Rocketman' and has borrowed a number of "bits" from the star in order to better get into character.
He said: "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."
And he joked he will then make a profit from the garments.
He added: "Then you can sell it on eBay."
Meanwhile, the British star - who has six-year-old son Louis with ex-girlfriend Rachael Speed - also admitted he didn't learn to drive until he was 30 and that was out of necessity.
Speaking at a cinema society screening of his new movie 'Locke', he explained: "I had to take my ex to the hospital to have our son Louis."
Tom finds it easy to make choices on what roles to accept.
He said: "It comes back to a very basic principle of story. Is it interesting? Do I want to be a part of it? Yes. How does it work? That's when you get back to a pragmatic sense of 'What's the practical next step?' I don't get up in the morning and go, 'I have to find a piece where I can look into someone's eyes.' "