Use these step-by-step instructions to build a rustic outdoor oven
You'll find most of the materials you need at a home center, except for the cardboard barrel, often used by movers. (You cut it in half lengthwise and use it to form the oven's curving top.) Look online under Barrels & Drums for a local source.
1. Arrange the 8 by 8 by 16 blocks on the ground to make a 32- by 54-inch base.
2. Cover with an identical layout of cap blocks.
3. Add layer of firebricks.
4. Cut the barrel in half lengthwise with a hacksaw. Center empty quart can on closed end of a half-barrel; trace and cut out circular shape. This hole will be the vent.
5. Score and cut two firebricks in half with a circular saw (halves measure 4 1/2 inches square).
6. Starting at back end of base, make three U-shaped layers of firebricks to support the half-barrel. Each layer is three bricks long and 2 1/2 bricks wide at back end. Position barrel on bricks.
7. Cut a 3- by 4-foot piece of the 6-inch wire mesh and shape it so it arcs over the barrel by about 1 inch. Bend and tuck
excess under bricks at side. Repeat with at least one layer of chicken wire, bending and folding edges over the rear and open
end of barrel.
8. Make door: Cut three 14-inch-long pieces from redwood 2-by-4. Join them together with screws running through two parallel lengths of redwood 1-by-3 across the front. Cut top into an arch that measures 14 inches tall at the peak and conforms to the basic shape of the open end of the barrel. Shape handle from excess 2-by-4, and screw to 1-by-3s. Center and tack flashing around door perimeter. Insert the can in the hole cut in rear of barrel.
9. Mix 3 parts adobe soil to 1 part Portland cement, add water, and mix with a hoe and shovel to the consistency of thick oatmeal. Be warned: it’s tiring and muddy work. Test that the mix holds together by squeezing it.
10. Working from the base up, pack the adobe-cement mixture firmly over and through the layers of mesh, leaving no air pockets. Pack mixture around the can, wiggling and rotating it to keep it from being trapped in place. Form arch for door by squeezing mixture into the chicken wire, and periodically inserting the door (with flashing attached) to check fit. Continue adding mixture until the coat is 4 to 5 inches thick overall. Let it dry slightly, then smooth the surface with a damp sponge and a wood "float" made with scrap lumber.
11. Wiggle the door and can, then cover the oven with damp towels and plastic tarp. Keep towels damp and oven covered for at
least a week while adobe hardens and cures (check daily). Remove flashing from door.