This print, from flexible filament (I used MatterHackers Pro series TPU), uses the Fibonacci64 Nano board, sold by Evil Genius Labs (https://www.evilgeniuslabs.org/fibonacci64-nano) along with two countersunk neodymium magnets (1/8" tall, ¼" diameter - e.g. https://www.kjmagnetics.com/proddetail.asp?prod=R422CS-P&cat=15) to make a wearable wristband (watch).
The magnets are held in place with two 5mm M2 flathead screws + nuts. The Nano is held in place with small M2 screws passing through the screw holes in the PCB. The battery connects to the Nano with stranded wire that is soldered directly to the nano at one end and wrapped around the screws holding the magnets on the other. The stranded wire is then tucked into the channel at the top edge of the band.
Some soldering required to connect the stranded wires . The magnets will not hold the battery strongly enough to keep it in place during vigorous activity.
The design file for this model is on Tinkercad: https://www.tinkercad.com/things/2ZmyqStjboP-fibo-watchi and is sized for a (small) women's wrist.
The author hasn't provided the model origin yet.