I bought a very cheap Chinese kiln on eBay, and it might have been fine for some purposes. But the element blew as soon as I tried for the maximum temperature which was claimed. I think the electronic controller was reliable, but I found the fragments of wire were hardened, which suggests that it was nichrome, which fails at a lower, temperature than kanthal.
About all I know about electricity is that I've never seen any, but it exists anyway, lurking in there and ready to jump out ajobnd zap you. But I found a most helpful seller of kanthal wire on eBay, who advised me on the diameter and length to duplicate the original 750 watts. The wire coils ran in open grooves in the rather soft insulating material, novaculite probably, which I didn't much like, but was handy for that job.
Later I bought one of these, used 5on eBay, for about $250:
https://www.efcocreative.com/efco-ki...30-v-1200.html th
The interior is one-piece ceramic, with the element concealed, which is a lot easier to clean. It only has an old-fashioned dial control, but a hole through which a thermocouple or digital thermometer could be inserted. The interior is only about six inches square, but you can do a lot with that.
I also have the ambition to make a Japanese sword and Renaissance-style rapier, which is nearly impossible to harden and temper straight by any process we know today. It would have to be hung and immersed vertically. I have the large kanthal element, an electronic controller and 5/16in. titanium rod for connections that won't melt. What I need is a large fireclay pipe, such as used to base used for drains but has long since been replIaced by plastic. I know of an unused piece in the old quarry buildings on an uninhabited island, where there are boat trips in summer. I'll have to check with the owners, but I am pretty sure they will say "Just take it."