Composing for the Car Music Project's instruments requires a bit of an open mind. Although the current set of instruments involves what appear to be fairly standard fingering and placement schemes for tuning, they're imperfect. "That makes the whole process -- from writing to playing -- a bit more interesting," according to Milbrodt.
Example: The convertibles, which are reed instruments, have finger holes patterned like wooden flutes. But the finger holes are not positioned perfectly, which makes it difficult to play in tune. When Milbrodt heard the instruments tested together, the idea of leaving them that way intrigued him. He says, "We got quirky harmonies that were hard to specify."
That made it interesting and fun, but also meant that music written for them needed to allow enough space harmonically so that every moment would not be a an annoying bleat. In other words, you don't want to create chords that are too dense to allow inadvertent subtleties to be heard.
The Car Music Project's current instruments are made from parts of Milbrodt's own car. He hired mechanics to take the car apart and metal sculptor Ray Faunce III to design and build instruments for him from its parts. He also hired musicians to test them and offer ideas.
Milbrodt liked the instruments' sonic imperfections, which eventually resulted in the Car Music Project's unique sound.
But an equally important design issue was ergonomics. Each instrument had to be comfortable: light enough, balanced, and shaped so a player could appear on stage with it for an extended period of time, without tiring.