Video narration
Rice mixed with stones is frustrating: picking through every handful takes time. Start with a kitchen sieve: rice crosses holes, while smaller pieces fall through. Gather cardboard, a perforated tray, DC motor, battery, switch, wire, and supports. Add side walls so rice travels across the tray, then secure it on supports. Fasten an off-center weight to the motor; its uneven rotation creates vibration. Wire the battery, switch, and motor in one circuit. Insulate every connection before testing. Feed a small batch. The machine is not cleaning by magic. Vibration moves rice across a sieve, but hole size controls separation. Test the holes with your rice and debris; adjust the holes or vibration if flow is poor. Smaller holes are not automatically better. A stone the same size as rice may still travel with it. You now have a vibrating sieve: run small batches, then hand-check the rice.