Anthony Liekens has a cool article on how to use an ordinary analog clock to display time in binary.

Both hands rotate and display two binary numbers, one for the current hour and one for minutes. The hands are cut out templates that carefully align with a backdrop to show binary numbers in the clock’s hour and minute hands. As such, the clock displays the current time in both analog and binary. Because the mechanisms of this clock do not require any electronics, but purely the mechanical rotations of the hands, it is a true “analog binary clock.”

Anthony’s analog binary wall clock displays 11:40

Check Anthony’s website for instructions and some pdf’s you can download and print to mod your own analog clock.