Here's what I'll build when I need a break from the house: a small bakeoven made of local clay, with the design and construction techniques based on bakeovens traditionally used in Québec.

These are outdoor ovens with relatively low domes and no smokehole. You build a fire in the oven, then scrape out the coals, wipe the ashes off the floor, add your bread, and shut the door. The retained heat from the fire bakes the bread.

Basic construction:

• Build the base. This could be stone, thick hunks of trunk, etc. Mine will probably be stone.
• Add the hearth. Traditionally clay; sometimes brick and recently concrete. Mine will probably be clay.
• Build an arched framework for the oven. I'll probably use flexible branches, maybe young beech. There are lots of other techniques. I'm not sure yet how I'll make the arch for the door--I'll probably use scavenged, non-galvanized metal.
• Mix clay and straw. I'll use clay I dug up when I dug my pond. You work the straw into the clay by kneading it or even dancing on it. The long fibers in the straw help hold the clay together.
• Build the dome. You make fat "loaves" of the clay-straw mix and stack them against the dome framework. The lower loaves are very thick, like 9 inches, to support the weight of the dome. Higher up you can go a little thinner.
• Build a roof over the whole thing so the oven doesn't melt in the rain.
• Let the clay dry.
• Build successively hotter fires. The framework will burn, leaving just the clay dome.

My main source of information is The Bread Ovens of Québec, which is a survey of old ovens and a detailed description of how one was built. The researchers even measured dome heights and calculated the optimal shape. The book has great information on the folk traditions associated with the ovens and their bread.

I've also seen an early edition of Kiko Denzer's Build Your Own Earth Oven.

Using old ways is a glorious way to make new things. The man with the best future is the one with the longest memory.
--Lionel Poilane, French traditional baker

Links:

General info on bakeovens with lots of links and books, from the Masonry Heater Association