This spare part is the yellow gear that attaches to the universal cylinder of the lock and serves as the transmission to the Nuki Ultra. Mine accidentally broke – likely because the gear has predefined weak points, probably designed to protect the motor from damage. I believe it can also break relatively easily with manual hand rotation.
Since there are currently no official spare parts available, I recreated the gear in CAD myself and can confirm that it fits perfectly.
However, it's important to mention that this model is primarily designed for resin printers. With a very fine nozzle (0.2 mm or smaller), it might work with an FDM printer, but I wouldn’t rely on it too much.
I hope you still find it helpful!
Use at your own risk. I accept no responsibility for any damage that may result.
The author marked this model as their own original creation.