Oval kiln with rectangular bricks, Castel Viscardo, Italy
Hoffman kiln, near Radzymin, Poland
Stacking a kiln with bricks to allow for ventilation and even firing is quite an art. As well, the places where they are touching during firing often get 'kiss marks', lighter patches of colour, so the stacking influences the final appearance of the brick.
One thing about having a non-rectangular brick, though, is that it is very easy to stack them in a way that allows the passage of air.
I ended up just laying them directly on top of each other, in two layers of three courses. This allows me to fire 105 bricks per kiln
Now, I just have to hope for the best...