Many hobbyists begin raising compost worms using shallow boxes, either homemade or commercially purchased, to create a habitat suitable for their red wigglers (Eisenia fetida). While these offer a good surface area to oxygenate the decomposing kitchen scraps placed in the bin, harvesting the worm manure can involve a tedious dumping and sorting of the bin contents. Continuous flow worm bins made from trash receptacles allow for a steady stream of compost to be removed from the bottom, while worms migrate up to fresh bedding and food at the top.
Mark an opening 12 inches across by 5 inches deep about 2 inches above the ground on one side of trash receptacle, using the marker, straightedge and tape measure. Cut the opening out using a utility knife. Discard the plastic rectangle.
Drill a 1-inch hole 3 inches above the center of the rectangular hole. Push a piece of conduit through the hole so that it crosses the interior of the receptacle and touches the far side directly across from the hole.
Place a small level on the conduit and level by centering the air bubble. Use the marker to outline the edge of the conduit.
Back out the conduit enough to drill out the marked outline. Press the conduit through the second hole so that it projects about 2 inches past it. Cut the conduit with a jigsaw to remove all but 2 inches of its original length from where you first pushed it through the receptacle on the opening side.
Hold your three-tined cultivator up to the inside wall of the receptacle and hook two of its tines on either side of the conduit. Mark a center point for additional conduit lengths so that once they are installed, the cultivator tines will be able to poke up and remove finished compost. For many cultivators, 1/2-inch gap between conduit lengths will work.
Repeat the process of drilling, inserting conduit, leveling the conduit, marking a second hole and trimming the conduit to fit until the entire bottom of the receptacle consists of a platform of conduit with consistent gaps. You may have to leave a gap of about 2 inches between either side of this platform and the sides of the trash can, because it is too tricky to create steeply angled entry holes for the conduit at the far sides of platform.
Place a half-dozen layers of newspaper across the platform. Add a foot of worm bedding, such as a soaked, torn cardboard. Add decomposing kitchen scraps and red wigglers. Cover the receptacle with its lid.
Remove castings beginning in about three months by scraping upward between the conduits using the cultivator.