Barrel compost bins are usually 50-gallon plastic barrels (food-grade quality you can get from restaurants) set on a stand, which are often simple saw horses. Barrel bins create compost in less time than traditional bins because they allow for more aeration, which allows bacteria to break down waste quicker. These bins are more ergonomic than most others: They do not require heavy lifting to turn the compost or to remove it from the barrel.
Build Saw Horse Stand
Measure, mark and cut the 8-foot lengths of two-by-four into six pieces that are 30 inches long (these will be the top of the saw horses) and eight pieces that are 32½ inch long (these will be the saw horse legs). Use the carpenter's square to mark the straight line at each interval and cut along the lines with the circular saw.
Measure the piece of ¾-inch plywood, marking three lines at 6-inch intervals along one of the short side. Use one of the 32½-inch pieces of two-by-four as a straight edge to draw lines. On the end of the board opposite the short side you just marked (the other short side of the same face) measure 15½ inches from the edge and mark a line across the width of the board.
Cut along this second line with the circular saw, creating a 32½-inch by 24-inch sheet of plywood. Cut along the remaining lines you made to start Step 2, creating four strips of plywood that are 6 inches by 32½ inches.
Measure and mark the 4-by-4 sheet plywood to create four 12-by-12 squares. Cut each square in half.
Create a I-beam using the two-by-fours (see image at http://shoppingmatchmaker.com/sawhorse.html). Mark a center line running the length of the two-by-four in four of the 30-inch pieces. Lay one marked board flat with the marked side face up. Run a bead of wood glue along the center line and lay the narrow (2-inch) side of an unmarked 30-inch piece on the glue line so the boards form a T and their ends are flush. Run a bead of wood glue along the top edge of the unmarked board. Lay a marked board on top, aligning the glue bead with the center line.
Secure the top two-by-four with wood screws at 6-inch intervals. Turn the newly created I-beam and secure what was the bottom two-by-four in the same manner. Repeat Steps 5 and 6 to create a second I-beam using the remaining 30-inch pieces of two-by-four.
Position the saw horse legs (the 32½-inch two-by-fours) by laying the ends of the boards into the crook of the I-beam. The outside edge of the two-by-four forming the leg should be aligned with the outside edge of the two-by-four forming the top of the I-beam. The inside surface of the two-by-four leg should be resting against a corner of the two-by-four that forms the bottom of the I-beam. This will position the legs on an angle. Secure the legs into the I-beam with wood screws. This creates two saw horses. (See image at http://shoppingmatchmaker.com/sawhorse.html)
Create braces for the legs using the 12-by-12 pieces of plywood. Place a piece so it spans the gap between the two legs on the each end of the saw horse just below the I-beam. On the inside face of the plywood, trace the outside edge of the legs and cut the plywood along the lines. Use this as a template to mark and cut the other three pieces of plywood. Attach the plywood with wood screws.
Position the 6-inch wide strips of plywood so they span the space along the length of the saw horse between the legs and attach with wood screws. These two steps will brace the legs on all four sides of the saw horse.
Attaching the Compost Barrel
Clean the 55-gallon drum to remove residue. Mark and drill a two holes in the drum, directly opposite each other, 18 inches from the bottom. Use the 1-inch drill bit to create holes. You want the holes to line up, so a piece of rebar can pass through the drum and act as an axle.
Drill six holes around the circumference of the drum and two holes in the bottom with the ½-inch drill bit. Two holes should be opposite from each other at 6 inches and 8 inches from the bottom. Turn the drum and drill two holes 10 inches and 12 inches from the bottom and opposite from each other . Turn the drum and drill two holes 6 inches and 8 inches from the top and opposite from each other. This creates offset holes in the drum to allow air flow.
Measure, locate and mark the center point of the I-beams on both saw horses. Drill a hole with the 1-inch drill bit. Slide the rebar through the holes in the drum made in Step 1 of this section. (The goal is to have the barrel suspended between the two I-beams, so it can be turned on the rebar axle.)
Insert one end of the rebar into the hole created in one saw horse. Insert the other end of the rebar into the center hole of the second saw horse. Fill the barrel with material to compost and close the lid.