I just remembered that one of my childhood books on electricity described how to make sparks with a battery, some wires, and a nail file; I tried it back ten, and it worked. Wire file to one battery terminal; brush wire lead from other terminal across the rough side of the file. Small sparks fly from where the wire contacts the file.
This method could possibly be employed to produce a spark effect for mock-up props.
Put a good inductor (coil) inline and a modest current will produce a surge of high voltage when the current is interrupted. The energy stored in the inductor will be dumped into a spark across the opening gap, unless it finds an easier discharge path.