Last weekend I helped build a clay oven, in hopes of using it during our upcoming Living History Week. We've had ovens from time to time, the first being built of broken bricks on site, covered over with clay and straw then disassembled with a hammer at event's end, the later one being built of clay over a tall basket and fired by burning the basket inside it. That one lasted a couple of years but was a bit delicate for moving back and forth to the site. Eventually its makers smashed it up cathartically.
After that we did without. But an oven is such a handy thing to have, and opens so many possibilities, that the idea was never quite given up. At last Joan bought clay and offered her patio as an assembly site, and Ina, fresh from a course on cob-building, offered her expertise.
I brought the basket.

Here Ina directs her two lovely assistants in preparing the sand-and-clay cob mix.

After the base has been covered in clay, the inner frame of the oven is established. Rowan is eagerly squishing clay into a sheet to begin covering it.

Halfway up with the first layer. Ina works up more clay and sand. We covered the frame with an inch-and-a-bit of cob mixture, then left it overnight. The next day we painted it with slip, then added a thinner layer of cob mixed with short-cut straw.

Some decoration to the top, as with some of the English examples, in a rope-twist pattern, and the youngsters could not be deterred from painting it over with slip once more.
It has to dry for a couple of weeks before we even think about firing it. We'd like to be able to put on a hand-cart and wheel it around, but we might have to settle for standing it on a couple of trestles.