Motor (Caterpillar) control via motor driver DRV 8835 at Arduino.

Measure the distance of the tip of the slider of the whistle with the distance sensor VL6180X to control the slide amount.

MEMIDION's casing was made with acrylic.

Place the parts on the black acrylic board, screw it and bond the side plate.

The top board is made of transparent acrylic and has holes drilled to arrange the MIDIController. NeoPixels is placed right above the slide part.

I put a black cutting sheet on the top board and cut out the slide part so that it can be seen. 

To make it easy to hold, a belt is attached to the back side.