The idea was originally for construction in wood. It came from a village technology handbook. I built mine out of iron and cement, and came up with the funnel plunger idea. The rectangular tank uses a special sheet metal with holes for plastering called Hi-rib. It is sealed with a cement-base sealer.
My method is to soak the clothes in detergent and water overnight, pump them for about 5 minutes in the morning, rinse them twice and hang them up on the clothesline.
It's good exercise, and it consumes no electricity.
Step 1: Inside the Washer
The funnels can be easily replaced if they eventually break, but they hold up quite well. The bright red funnel was recently replaced.