Composting utilizes the natural breakdown process of organic materials into soil to produce a soil amendment rich in organic matter (see References 4). As a natural process, composting doesn't require any special equipment to get started, and while you can purchase a costly composting unit, a sturdy plastic trashcan works equally well. You can use trashcans to set up indoor or outdoor compost bins.
If you don't have a lot of space in your yard for a compost pile or live in an area prone to pest problems, setting up an indoor composting unit may be ideal. Two trashcans --- one large and one small enough to fit inside the first with room for the lids on both --- will effectively compost materials while controlling odors. Set a brick or cinder block in the bottom of the larger can and spread sawdust, straw or wood chips around it. Drill 1/2-inch holes in the bottoms and sides of the smaller can, set it on the brick and cover both cans. (See References 4) The sawdust will absorb any liquids that drain from your compost and minimize odors. (See References 1)
A sturdy plastic trashcan can also make an easy and inexpensive compost unit for outdoor use. Begin by drilling 1/2-inch drainage holes along the sides of the can. You can also drill drainage holes in the bottom of the can, or you can remove the bottom of the can completely and let your compost rest on the bare soil.
If you don't remove the bottom of the trashcan, add about 3 inches of sawdust, wood chips or straw to the bottom of the can to help absorb the moisture draining off of the compost. (See References 2, page 39)
The microorganisms in your compost need the right balance of oxygen and moisture in order to work most effectively. Too much moisture squeezes out the oxygen and kills off the fast-working microbes. In an open compost pile or in containers designed for compost, air flows easily into the compost and extra moisture drains down into the soil, keeping conditions ideal. In a homemade unit, make sure that too much water doesn't collect in your compost. Mix your compost frequently to break up clumps and distribute air throughout, then apply the squeeze test: take a handful of compost and squeeze it. If more than a few drops of water leak out, add extra straw, sawdust or paper shreds to soak up the extra moisture. (See References 2, pages 7-8)
Especially when composting indoors, you'll need to control odors. Bury food scraps at least 10 inches deep in your homemade composter. (See References 1)
Odors can also indicate a moisture imbalance, a problem you'll need to watch out for when using homemade units. A rotten egg smell indicates that there's too much water in your compost. Add sawdust or straw to soak up the extra moisture. (See References 3) If this problem persists, drill more holes to improve drainage.