I’ve been toying for a few years in sketches with what a playlist should look like. It used to be an album cover, a square design that was retried from a shelf and taken to a player, or a cassette, decorated and owned with layers of patina. I remember a friend who had connected a barcode scanner up to their stereo so that they could start a cd playing (from the copy on their digital library) by scanning the barcode – giving the cd cases continued significance and making use of existing social gestures for selecting music to play.

Now that playlists are digital, a web link or usb flash disk seems like an insubstantial and transitory alternative. I would like to load playlists of music in to objects that are meaningful. These can then be given as gifts, kept on show on the coffee table or mantelpiece, or stored like a cabinet of curiosities. Objects could be created for the task, embedded with rfid tags like skylanders, but for me it would be better if I could teach *any* object my playlist.

Sensing any handheld-sized object, whether it is a seashell, a toy car, a broken cup, a rock, a personal 3D printed shape, and so on, would require a whole palate of sensors to have a chance of being robust. Place the object in a box or on a pedestal and we could imagine using computer vision for contour, pattern and colour sensing, and maybe weighing the object too.

I chatted about this idea with participants at the Making Digital Physical CX workshop. One suggestion that grew from our discussion was the idea of teaching objects a playlist should happen in real-time. This was how cassette mixtapes used to be constructed and it meant they retained significance through the time and effort invested in making them.

Another dimension to using arbitrary objects is that more than one person might ‘overwrite’ mass produced objects. All starbucks cups look the same, so the mix you taught your cup yesterday might be Beiber by now. This creates an impetus to seek out unique objects, or at least to modify them to make them unique. It also suggests a gesture of 3D printing for sharing a mix, or teaching your secret club decoder ring a secret club theme tune.