Intensifying the fire with blowpipe
If you can't decide if you really want an earth oven in your backyard, or if you're not sure how much work it will take to construct one, then consider building a mini earth oven first. It should only take a couple of hours of your time, but it will give you an idea of what to expect if you're ready to build an "official" oven. Although the mini oven is tiny, it is not so tiny that you can't bake little things inside. You could bake pita breads and even six inch pizzas.
Your brick floor determines the oven size
Workshop participants construct a mini oven on top of oil drum
Cutting an exhaust hole (which is covered during baking) makes it much easier to start fires in mini ovens