A wearable heads-up display for downhill sports, showing live speed, altitude, and elapsed time in the rider's field of view so the data is glanceable mid-run instead of something you check at the bottom of the hill.

The system runs on a Raspberry Pi Zero W, chosen for size and weight, since anything mounted to goggles is carried on your face for hours. A GPS module feeds position and velocity to a Python interface driving a compact LCD, with the whole system running Raspberry Pi OS Lite to keep boot time and overhead down on limited hardware.

The mechanical design is where most of the iteration went. The frame was modelled in Fusion 360 as a multi-material assembly: rigid PLA for the structural chassis carrying the Pi, display, and battery, and flexible TPU for the sections that conform to the face and helmet. That split solves a problem a single material cannot, since the electronics need a stiff mount that holds alignment while the contact surfaces need to flex against a moving head. TPU also prints badly at default settings, and dialing in reduced speeds with cooling disabled took considerably more trial and error than the rigid parts.

Weight distribution drove the layout throughout. A display assembly that is front-heavy becomes uncomfortable within minutes and unusable over a full day, so battery and compute placement was a balance question before it was a packaging question.