The following is an excerpt from Making It! Radical Home Ec for a Post-Consumer World by Kelly Coyne and Erik Knutzen (Rodale, 2011). The excerpt is from Section 5: Infrastructure.
Composting is the ultimate form of recycling, so shouldn't the container used for composting also be made from reclaimed materials? One of the most ubiquitous castoffs in our cities is the humble wooden pallet. It takes just a few minutes to hook together a few pallets to make a phenomenal compost bin.
• 3 wooden shipping pallets, all the same size (Find them behind stores.)
• Attachment hardware: your choice of screws, nails, bolts, twist-ties, or wire
• Scavenged boards to act as slats for the front of the composter (2x6s, 2x8s, etc.), at least 3 feet in length
• 12 to 16 total feet of 2x4 lumber (You can piece together scraps, if necessary.)
• Chicken wire, hardware cloth, and/or flattened cardboard boxes (optional)
Putting It Together
1. Choose a level site, preferably on soil and in the shade. Orient the back pallet of the compost bin with the slats running vertically and on the inside of the bin. Attach the side pallets of the compost bin to the back pallet with the slats running horizontally and also facing in. Alternating the orientation of the slats makes the bin stronger and gives you a nailing surface on the front. Connect all three pallets at their corners with screws, bolts, nails, twist-ties, or wire. Predrill the holes if you are using screws or bolts, as pallet wood splits easily.
2. The front of the bin can be left open, but it's neater to place slats across the front. The slats also allow you to build a taller pile. By using stacking slats, you can add or remove slats to access the pile at different heights. Most pallets measure 3 feet across, but some don't, so measure the width of the front of your bin. Cut three or four lengths of sturdy 2x6 (or wider) lumber to the width of the bin to serve as slats. How many lengths you cut depends on how wide the individual slats happen to be, but most likely four slats will do to close the front of the bin.
3. Make guides for the front slats by cutting four pieces of 2x4 lumber to 48 inches (or whatever the height of your shipping pallet happens to be). Using nails or screws, attach two 2x4s to the inside of the bin and two more to the outside of the bin. Slide the slats horizontally between the guides.
4. Line the walls of the bin with the chicken wire or hardware cloth to critter-proof it and hold in loose materials. To help retain moisture in dry climates, line the bin with cardboard: Flatten cardboard boxes around the inside walls as you fill the bin. Depending on your climate, you may want to improvise a cover for the bin. We've used both cardboard and plastic tarps as covers to keep out rain and retain moisture.
Add two more pallets to one side of this bin to form a two-bin system. Add two more pallets to the opposite side to form a three-bin system. Having multiple bins makes it easier to turn the pile.
With a two-bin system, you just need one set of front slats. To turn the pile, you transfer the front slats to the next bin as you fill it. You can then turn the pile back and forth between the two bins as often as you like, transferring the slats as you shovel.
With a three-bin system, you start out building compost in one end, turn into the next, and then let it finish in the third and last bin. After you turn your initial pile into the middle bin, you can add new compost to the end to start a compost assembly line.
For more fun ways to use recycled shipping pallets, check out the blog post "5 Ways to Upcycle Shipping Pallets into DIY Furniture."