How to make it
The most difficult part is to empty it because most of old Apple product, and specifically adapter, are not supposed to be fixed or opened. There's no rule to empty the adapter. Just use your imagination and a screw driver without breaking the shell. Then using the drill, just use the drill with tiny bits (and progressively increase the size of the bit until you get the right size), make a hole in the apple logo to fit the clock mechanism.
This is a cheap project, the clock mechanism can be taken from an old clock or does not cost more than $3. You can also buy a $1 clock from Ikea and take the mechanism. I would prefer to use thinner hands, they are a bit too thick and are hiding the apple logo to0 much. That's all I had in stock this week end.