Check out the manufacturers of automatic dog feeders. There are feeders with different mechanics. All automatic or with a dispenser, which operates by the animal itself. (Don’t know if this is relevant for dogs in the sense of overeating).
These things are delivered by transport companies. However, to design this kind of device from improvised materials will not be difficult.
Quite a few sheets of plywood, a couple pieces of hardware from the landfill, a window lifter motor or the lock actuator from the best cars in the world “Lada” and any electronics, for example, 1-wire for automatic or remote control.
