Two types of electrolyzers have been discussed on the web: Parallel plates and concentric cylinders. Parallel plates are easier to construct. They are typically made of 316L stainless steel, a nickel alloy. The plates must be exhibit a rough surface to facilitate releasing the water gas bubbles. Roughing can be done via sand paper, sand blasting, or conditioning in potassium hydroxide solution running standard electrolysis. The plates are spaced closely (1 mm or less) and are electrically isolated from each other. (They must not touch or short circuit together.) Only the outside plates are connected to the pulse driver circuit. The remaining plates are electrically floating and are thus capacitively coupled. Water covers the plates, and violent bubbling can be observed between them when the apparatus is running. The water gas accumulates at the top of the chamber and it is directed into the motor.

Be blessed, Joshua.