THis latest build looks better than previous, looks more like it might work.
But I can't help but think, even if you value your time at only $5 per hour. The time and the money you have shelled out in propane and parts, is considerable. You could easily have bought a professional grade, or at least professional artist's grade kiln. You have been messing around for nearly a year, re-inventing a kiln. You could, for just a few hundred, buy a used kiln, or for a few hundreds more, a new one. A commercially manufactured kiln would be workable dimensions and have burners the right shape, and air vents in the right locations, and all the other variables covered, to be able to make decent pottery.
I don't feel the need to learn flint napping everytime my butcher knife gets dull. My niece's husband is a PhD anthropologist, and he feels he needs to learn flint napping, but that is to prove some obscure historical point about paleolithic technology, not because he needs a sharp knife in the kitchen.
Your experiments are interesting, and I enjoy following the progression, but I think if you really wanted to make bonsai pots that are durable enough to actually use for bonsai, you should really just invest in a decent kiln.
I’d be glad to offer any assistance, from my experiences, I could.. we could avoid MANY ..um.. “pitfalls” I discovered.
