Philly-based artist Bradley N. Litwin is a self-taught "sculptor of kinetic automata" who has worked on everything from medical product manufacturing design to museum exhibit design and electronics equipment prototyping, among other things. He also cranks out insane machines like his Quadrotapult, below. (Check out when the camera angle switches at 0:28 so you can see what's actually happening.)
His Octapult is similarly nuts--check out that plate in the middle:
And if you were to receive a holiday card from Litwin, it would probably look like one of these:
Check out more of his stuff here.