These videos show how you can build a functioning biodigester using paint buckets. These digesters produce only about 3 minutes of gas per day under optimum conditions, but this is enough for demonstration and the slurry is useful for fertilizing houseplants. They take a cup or two of food wastes per day.
Our research group in Makati Science High School would love to know the materials for setting up your version of the mini-biodigester. We assure you that solar cities will be cited in our paper when we make one for our research.