And the people took their dough before it was leavened, their kneading troughs being bound up in their clothes upon their shoulders.
Exodus 12:34

A bread oven can be a big and expensive piece of equipment. On the other hand, it can also be a temporary construction. In this photograph of a Gypsy encampment taken in Hungary in the 1880s, one can see an adobe bread oven in the lower left hand corner, in front of the woman smoking the pipe. Less visible are dough boards stored on the roofs of the houses.

I think it fair to assume that this ovens was made with soil found in or near the encampment. A form for an adobe oven can be created with a frame of green branches or over a form of wet sand or dirt. For good instructions on building an adobe oven with a frame of green branches see The Bread Ovens of Quebec. For good instructions on building an adobe oven built over a frame of sand see Build your Own Bread Oven by Kiko Denzer.

The bread oven pictured here is not insulated. However, with a fire burning on the inside while breads are being baked, it would bake large quantities of flat breads, and the oven walls will store enough heat to bake a single batch of yeast- or sourdough-leavened loaf breads. Notice a flat stone in the foreground by the woman smoking a pipe. This could have been used to roll out dough. I own a similar-looking stone that was used in Rajistan for rolling out chapatti.