Sony recently learned that you are selling a case for carrying an iPod personal stereo that is made from a WALKMAN tape player. The product is being offered at your website at www.retropod.com.Link (Thanks, 555Rgne!)
Your use of casings for such a purpose is a clear infringement of the SONY and WALKMAN marks because it is deceptive. Consumers likely will be misled and deceived into believing that Sony is somehow connected with the iPod personal stereo when in fact it is not. (and now the important part) Moreover, they will be misled into thinking that Sony is backward in its design of products and is going away from miniaturization, as the size of the tape player housing is quite large by today's standards.
I write books. My latest is a YA science fiction novel called Homeland (it's the sequel to Little Brother). More books: Rapture of the Nerds (a novel, with Charlie Stross); With a Little Help (short stories); and The Great Big Beautiful Tomorrow (novella and nonfic). I speak all over the place and I tweet and tumble, too.