What is with the plastic?
At this moment in time, the photos that have been shared are using prototypes made with Multi Jet Fusion MJF 3D printing. You can learn more about MJF here. 3D printing enables us to iterate fast on plastic components, we also use SLA printing frequently. 3D printing is a prototyping tool, not a production solution. As outlined in the schedule, we will continue to build prototypes with 3D printing in DVT-1 and DVT-2 but transition to injection molded plastic for MP.
Why does it have holes?
The tracking system relies on detecting IR light emitted from the SteamVR Basestiation. The optical properties of the 3D printed plastic are more difficult to control than in Injection molding. For this reason, we simply remove the material above the sensors. It is a tactic just for prototyping, Sensors will be covered in the MP version of Tundra Tracker.