Levuccio, you seem to know the answer to your question already, just perhaps looking for support?
In answer to your question, yes there are ways to make vessels which shall hold bonsai at home in the oven. These I believe do not qualify as "pots" as it needs to be fired. Like Matt said, you can indeed make your own kiln at home, which I shall indeed do in the near future... Feel free to join along with me and I'll give you detail how to make a nice little kiln at home. Check google out and "Home made forges" The forging community seems to be a little more open minded, about home DIY than the potting. A home made kiln can be done in ground with forced induction, or in an upright glass matting kiln also with forced induction.
What you may be after at the moment is the cure for cracking whilst in the oven. Remember you are only going to get a brittle vessel without 1000 degree firing. I cure/harden clay to form vessels by putting it in the oven. The reason it is cracking is because you are bringing up the temp in the oven too quickly without air drying the clay first. Put it out in the sun for the day to remove moisture, then put it in the oven on 200 with the door slightly ajar for 2 hours, then close the door and bring it up to full temp.
I just put it straight in without drying in the sun with the door ajar on high for an hour then close it and bring to full temp.
Your clay will still not be fired and may absorb moisture still. I coat mine with clear acrylic gloss to stop the water permeating the unfired clay...
This method is similar to the making paper pots.
This thread of mine shows all unfired oven baked vessels. So it is possible, just don't call them pots because they are not, merely vessels... Don't drop them either because they might crack... but then again so may a pot if dropped.
viewtopic.php?f=29&t=4000 viewtopic.php?f=29&t=3981
I'm actually about to go mix up some clay and make some lil' shohin pots, Matt's recent efforts have inspired me.

Regards, Mitchell.
"It is one thing to shape a tree into form, but when you are able to convincingly deceive ones perception of reality, something much more is accomplished than just a simple bonsai."
"In a perfect world, we would all be giants and all plants Bonsai."
"Grow big, finish small."
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