Making a servo tester using an Attiny85 micro chip, Attiny45 also works for this project. This diy servo tester is as good as ...

Arduino Defined Arduino is described by its makers as “ an open-source electronics prototyping platform based on flexible, easy-to-use hardware and software,” whatever that means.

The button states could easily be read by using an Arduino’s analog input. A Pro Mini model was chosen for its small size as it could be housed in the radio compartment of the dash.

DIY musical instruments are their own thing entirely, but if you're looking for a place to start, Adafruit has a guide to building your own MIDI controller using an Arduino.