I came back from holiday vacation to discover a Shapeways box waiting on the doorstep. Inside I found two copies of the 3d printed cube enclosure, which came out looking nice, fit together well, and let enough light through to show up in sunlight.
The light is a little unbalanced in the corner but that's more an issue with the LED placement than the cube itself.
Starting with a fork of the ATTinyTemp enclosure i created a rounded cube enclosure for the blink(inch) in OpenSCAD. It is just a bit larger than an inch^3, and thanks to the original parametric design the only real effort went into making sure the hole for the USB plug was the right size.
While I wait for the PCBs to arrive from OSHPark I'll use an equivalent breadboard to start developing the firmware and driver.
My current conception of the driver exposes a service with a single method:
setRGB(r, g, b, message=null)
Scripts can go about their business (e.g. poll the bitcoin price) and call the service when they want to display some information (e.g. setRGB(255, 0, 0) when the price is declining). The optional message parameter can be used to explain the change, potentially showing up as an unobtrusive notification (like Growl).