If you already found your bend points, you're going to need to figure out what components you're going to use. If the effect is a drop or raise in the pitch, go find a variable resistor of some sort. This can be a potentiometer, photocell, and a bunch of other things.
If it's your first bend (which since you're asking this, I assume it is) you may want to think about using body contacts. A body contact can be any metal bit you can find. Screws and thumbtacks work great. If you use thumbtacks, just poke them through the case of the toy and then solder your wires to the metal points poking through. Solder the other ends of those wires to the bend points on the circuit board.
If you find a glitch, use a switch. There are TONS of different switches. You'll want to find one that is SPST (Single Pole Single Throw). These can either be a toggle switch or a pushbutton. Just drill a hole into the device your bending to mount the switch and then from the wires coming from the bend point, solder them to the two lugs coming from the switch.
Hope this helps. If you have any questions, don't be afraid to ask.