The popular Hollow Clock 4 is now thoroughly improved and refined.

• The ring is much thinner and neat (only 7mm) with indexes.
• There are no screw heads on the exterior (except the center of the hands).
• USB-C power inlet is placed on the back of the base.
• Ratchet mechanism makes the clock reliable against the slippage (out of step) of the weak stepper motor.
• Accuracy of the clock is much improved by the crystal oscillator of RP2040 based microcontroller.
• Easy time adjustment method (pull out the display ring, adjust, then insert to the base) is carried over from the previous model, but the ring is now securely fixed.
• Totally redesigned to exploit the texture of build plate and layer lines. Frontal surfaces of the clock are textured by the build plate.

June 5, 2024 : "base-front" and "base-rear" are slightly improved for reliable USB-C connection.

July 13, 2024 : Back cover for "Seeed Studio XIAO" series micro controller is added.

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