Nothing new nor earth-shattering here; if you're experienced with pendulums you can (or even better,
have a spectator) do all this stuff for real without having to resort to forces, stacks and peeks.
Essentially you have three cards revealed by a pendulum and most of the time YOU are the one making
it swing. When you don't, you just look at however the pendulum is moving in the spectator's hand
and say, "Oh, Nine of Diamonds." That's pretty much what you're getting here.