A primary coil of diodes. Would that work ?

[floodrod]

It looks decent. But it only pulses one polarity it seems.

For half that price you could get an Arduino, h bridge, the hall sensors, resistors, etc. Which would allow you to trigger it to run motors, flip polarities, and more flexibility.

Just my opinion.

[fxeconomist]

But the question is now, what kind of diodes would work ?

The elegant, strong legged diodes have zinc legs, and the resistivity of zinc would reduce EMF by 3 times.
I would like something with copper...

Wonder if I could actually bury the diode legs in sheathed copper wire..., but what will that do to currents and voltages...