I had one custom built for a 10x12... 8' peak, 5' walls. Guy I got to know in MT designed it and I had it fabricated to his specs.
Gads...it was made of good heavy metal to not burn out, but he wanted a box on the stove too big for the pipe he asked for...it would NOT draw.
A good, commercial, well-proven stove that might need the bottom replaced periodically beats one that won't draw!
I laugh about that stove every time I see the Tom Selleck movie, "Monty Hall!" Bad stove is bad juju!