BBC business correspondent Robert Plummer has filed the following report:

If you still buy music on CDs or vinyl from record shops, you have to take it home before you can hear it, unless you carry a portable player around. But what if the record could play itself?

The idea is not as weird as it sounds. Back in the 1970s, some promotional flexidiscs - records pressed on extremely thin plastic - actually came with a primitive cardboard gramophone attached.

All you had to do was place the steel pin "stylus" on the edge of the record and rotate the disc with your finger to hear the sound encoded in the grooves. Now, nearly 40 years later, someone has come up with another sound carrier that has the playing equipment built in. And, quirky as it seems, the result could help make physical music formats cool again in the digital era.

The Playbutton is a digital music album in the form of a badge, providing album artwork that you can wear. Pin it to your lapel, plug in a pair of headphones and you can walk down the street displaying your musical taste as you listen.

"It's a small object, perfect and immediate, that you can hold in your hand," says Nick Dangerfield, founder of the New York-based Playbutton company.

Mr Dangerfield says he came up with the format in response to a widespread feeling that people were "tired with CDs", but finding digital music downloads "not entirely satisfying".

"I thought about giving a new use to digital files by putting them in a dedicated player. It's an iconic form that gives you the chance to show your affiliation," he says.

Promotional flexidisc from the 1970s for Radiomobile car radios The self-playing record was invented in the 1970s

"It shows that you've purchased the music, so it shows your support for the band."

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