Google releases Fitbit Air blueprints to let anyone make bands, accessories 

Google is leaning into the Fitbit Air’s swappable pebble design to let anyone make their own accessories. This move is rather Google-y and reminiscent of the company’s earlier days.

Noting how the “community has already come up with innovative and creative new ideas to make the Fitbit Air [their] own” since launch last month, Google is “officially releasing the hardware specifications and accessory design guidelines for the Fitbit Air tracker to the public.” For example, owners have already found their own bicep band solutions.

This information would typically just be available for third-party accessory companies, but Google wants to open things up to “independent designers and artisan makers.”

Google today released Fitbit Air 2D CAD drawings [PDF] of the pill-shaped pebble that houses the sensor and the “sleeve” used by the Performance Loop Band. 

These CAD drawings include crucial mating dimensions, tolerances, and mating force specifications – including attach and detach force – to help you build a high-quality accessory band.

A Google Store page lists other things developers should keep in mind:

• Sensor Clearance: “We recommend that the optical heart rate and SpO2 sensors on the base of the tracker remain entirely unobstructed and maintain flush, consistent skin contact. To get the best performance while a user is moving, your band should be designed to maintain a steady, gentle pressure against the skin in the sensing area.” 
• Sensor Pressure: “For optimal PPG performance in motion, it’s important to design accessories for sustained contact pressure in the sensing region. Recommend pressure for best performance is 35 mmhg (0.68psi) minimum for nominal wear.”
• Secure Retention: “The tracker uses a tension-based snap-in mechanism. Your enclosure should follow the provided CAD tolerances to ensure the sensor remains securely locked in place during rigorous movement, while still being easy to remove when swapping bands.”
• Google goes into detail on using skin-friendly materials in accessories to “help prevent any skin irritation or allergic reactions.” There’s a list of chemical limits, environmental standards, and testing requirements.