i'm thinking of making a pet food feeder for my dog. what i have in mind is some 2" pvc pipe oriented vertically, with some kind of flap on the bottom end. i'd fill the pipe w/ food and at some preset time, the flap or whatever on the bottom of the pipe opens and the food falls out. i was hoping to activate it w/ an appliance module. so...any suggestions on what i can use as the flap and the opener? thanks!