This is a clockwork, built with different gears, technic bricks and other parts. It is designed as a built-in, so not visible from outside. Only the clock-face and the minute and hour hand are meant to be visible at the end. The clockwork itself would need certain space inside your construction, whatever it is (e.g. a building).
The pictures and the linked video are only my suggestions for the clock-face and the hands. After you built the clockwork, you understand its principal and with that, the final clock design depends on your wishes, needs and abilities. The clock-faces and clock hands in the pictures, video and the instruction itself are only one of “endless” possibilities.
With a very little adaption, you could make it a “workable” clockwork, with real moving minute and hour hands. For that, a motor (and battery box) would be required. The instruction will show you the necessary steps to do that. The “workable” clockwork is running faster than a real clock, because of the smaller scale of the “brick world”. The final speed would depend on the motor you use to turn the hands. The clockwork is designed in a way, that you can fix different motors (e.g. M, L or XL-motor). Again, the instruction shows you how. Minute and hour hands move in different speeds, almost as in real clocks. This is realized with different gear reductions.
Finally, this is my creation of a clockwork but maybe not the best way to realize one. So, feel free to create your own design and take my work as inspiration.
MOC stats (only the clockwork itself, without clock-face and hands):
Length: 16.8 studs
Width: 11.7 studs
Height: 11.6 studs
Weight: 140 g
Parts: 131
A video of the working clockwork you can see here:
Video music: https://www.bensound.com
Disclaimer: I am not responsible for any damages or injury on parts and humans happen while following my instructions. Everything you do is your responsibility and under your personal risk.
Link to the instruction and sticker files:
Link to more pictures of the model: