Step 1: Gather Your Materials (And Tools)
ONE Cheap-o clock mechanism w/appropriate washers, spacers and (of course) clock hands.
FOUR Plastic drinks bottle tops, or appropriate diameter equiv.
ONE Pillar drill w/9mm, or appropriate size, drill bit (depending on the clock mechanism of your choosing).
ONE Hammer and awl.
SOME E-poxy resin if required.
AND ONE Set of pliers to tighten said clock mechanism.
Got them? Good, then let us begin.
Step 2: Constructing The Clock Face
Make sure that they do not protrude from the lip of the lid too much, within about +5mm tolerance.
By chance the plastic tops that I chose/found fitted inside the lid almost perfectly and required no methods of adhesion other that friction, although you may want to use a bit of E-poxy resin.
When the tops are in place, mark the centre with an awl and make a small dent to help guide the drill. Accuracy is not of great importance, but at the end of the day it's your clock.
When you have made the dent with the awl then you are ready to drill the hole for your clock mechanism. I used a 9mm drill bit, but it really depends on the mechanism that you are using.
When you've drilled the hole, you may want to file it down slightly, but I chose not to because I didn't want to risk scratching the front of the clock.