Designing an instrument:

• What gestures will control it?
• What sensors do you need for those gestures?
• What will need to be done with the sensors to make them "playable", e.g., mounted on wood, put in tubes, duct-taped to your head?
• How do the sensors translate into switch contacts, or 10KΩ resistors, or +5V DC sources, to use with the Arduino? Will there need to be supplementary electronics?
• What processes will be applied to the MIDI data coming from the Arduino?
• What will the instrument sound like, and how will the sound be controlled by the gestures?

Assigning tasks:

Specifying and obtaining sensors.
Specifying materials to make sensors playable, i.e., the human interface.
Wiring the sensors making the wiring robust.
Adding circuits to process sensor data.
Writing the Max patch to process the data.
Designing the Reason patch.