Of course you will not weld with such a welding machine in everyday life, but for a hopeless situation you will surely help out. And besides, I have not yet seen a simpler device. . .
As you can see, it consists of only three batteries and thick wires. Electrodes are not very large in diameter. But for welding medium-sized objects it is quite suitable.
There is also a significant plus - it works without an outlet, which means you can cook anywhere!