A close friend (and big Daft Punk fan) approached me for help repairing a Guy Manuel helmet he had sitting on a shelf for nearly 10 years. It was originally purchased online and arrived in shambles but the outer shell and some of the electronics were still salvagable.
The orignal helmet (shell and visor) and a few PCBs were untouched, but virtually every other component inside was custom designed and rebuilt using CAD, 3d printing, and my software and electronics knowledge.
After completing design & fabrication of the new parts and circuits, I mounted them inside. All parts were designed so they could be removed with a screwdriver for repair if ever needed. Custom animation sequences were coded on an Arduino Nano Every (housed in a custom enclosure) along with "mode" buttons to cycle through each.