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.

If you have some questions, please use "comments" feature of this page. Do not use personal message function to solve your specific problem because I receive so many messages. Share your question, it is worth for everyone, and the other people faced to the similar problem might answer it. If you have essentially personal question (such as license of this design) , use personal message system.