If this is modified into a postbox forge, I cannot recommend it highly enough.
The 12 kg furnace (probably the 6kg as well, though I have not used it) has serious potential and a few serious drawbacks.
The stainless shell is good, it could have been better but for the price point it is quite good. All of the materials used are pretty standard and so of expected quality. The Kaowool/Inswool is exactly what Id expect as are the firebricks. The burners work as expected.
Basically, for the price this is a good purchase. But it does have some very serious, but fixable flaws.
The Inswool fabric was unsealed. This is actively dangerous to your lungs, it should be sealed behand some kind of refractory. I used Satanite, it worked perfectly. Ridgidizer is a temporary fix, use a refractory.
It comes with a pair of tongs that are actually very dangerous to use. If you use them to pull the crucible out of the furnace, you will put point stress on the crucible and potentially break it while it is full of molten metal. Proper lifting tongs and a second pair of proper pouring tongs would be a very wise investment.
When running the two burners, the fuel draw is faster than a small 20lb propane bottle can supply continuously. The single bottle begins freezing, the flames begin pulsing and the flame head can travel into the feed pipes, putting the flame head right at the brass tip of the torch. You will need to chain two bottles or get a larger bottle either should fix this by increasing the gas flow.
The burners do not have an air choke, forcing you to have the gas pressure high to keep the flame head inside the furnace. A simple piece of pipe slid over the air intakes would allow you to throttle the flame better.
Finally, I turned mine into a postbox forge by cutting some holes in the sides, a little down from the lid and bending the metal skin down as a shelf. I doubled the Inswool and lined it with Satanite. I shaped the Satanite around the burners to integrate the flare into the refractory, so I didn't have to modify the depth of the burners. It works fantastically.