Worm bins can be any shape and size, and many are sold commercially already complete and just waiting for worms and waste.  One of the easiest is to use a large plastic storage container that provides 2 square feet of surface area for worms. This means the bin can handle up to 6 pounds of food scraps each week, no more. It is big enough to handle the waste for a one person household.  Two bins can handle two people, and so on.

Let the following guide you: