Wow, you get to a point that I would call 'done' (second to last) and then you add more lighting! That's really interesting, and it really makes your pieces pop in a different way than most others' artwork. Thanks for sharing your process with us!!
Actually if I may... I do not wish dispel the obvious magic you see there in that world, but do wish to dispel the need for it to run the clock. The magic there need be put to better use than simply running a clock. The hands of the clock (hours and minutes) are fixed into 2 separate 6 foot round glass plates, each of which have gearing of different sizes affixed around their circumference. The gear you see inside at the upper right is fixed through the wall and is connected to the power source inside (and out of view to the right), and to the glass plate gearing with other gears behind the visible gear. Inside the wall this other drive gearing mates up with the clock face gearing. That's why you don't see the gearing, and it was done purposefully this way so as to not block the view out or the light from entering into the Clock Tower apartment. The Roman numeral hour markers are of wrought steel design and are affixed to the outside wall in front of the glass plates.
Well I left out the fact that the round hour and minute hand plates are supported and roll on 2 rollers hidden behind the wall at the base of the clock, and of course 2 guides positioned and hidden at the top stabilize and keep the plates aligned with their gearing that was described above.