Brick Oven Dome Building

The floor of the oven is laid herringbone style with common firebrick and the dome bricks are cut from the same bricks.
Calculating (or drawing) the precise angle for the brick comprising each chain (the ring of bricks making up the dome) allows me to lay the bricks with thin seams. This strengthens the dome as each brick is locked into place while the mortar provides the seal and the adhesion needed to proceed rapidly.

The mouth of the oven is angled outwards so that access to the products while baking is maximized at the same time as the mouth of the oven is kept to the correct proportion for retaining heat in the oven.
This is very similar to the bakery ovens I found on my visit to the excavated ruins of Pompeii, in Italy.

The vertical bricks act as a door-jam and will support angle-iron for the mouth opening (in the case of this portable oven) or an arch (when this design is a stationary oven).