My entry for the Birdhouse Challenge:
A traditional Swiss Cuckoo Clock with a real bird in it!
Disclaimer: Swiss punctuality not guaranteed.

Print all parts (twice for the weights).
Attach a wall clock mechanism with it´s hands to the clock face part.
Fit the face in it´s place in the house part.
Hang weights with a piece of cord through the holes.
Persuade a bird to live at your birdhouse (Cuckoo preferred)
Don´t expect the bird to sing at o´clocks.