I recently came across these two projects which sparked a thought about drawn interfaces, or interfaces that are created on the fly.
The first project 'Singing fingers' is a music making iPad app, where you drag your finger across the screen and it records your voice or any sounds at the position of your finger. The pitch is translated to colour and the brush size determines the volume. You're then able to playback the sounds on your musical canvas. So it essentially maps sounds or music to your drawing in realtime.
The second project 'SketchSynth' is a drawable control panel, which allows you to draw sliders and buttons on a piece of paper, which is recognized by a camera and allows them to carry out functions.
What I find cool about this is that we're talking about interfaces that don't exist until they're created. Imagine having an interface that's completely flexible, where if you needed a slider to turn down the volume, you could just draw one and it'd be usable. Kind of like on-the-fly programming, where you create functions to solve problems, but instead you're creating controllers for an interface.
PS. For some reason this reminds me of those Looney Tunes episodes where someone needs to escape so they draw a hole in the wall and it becomes a portal.