Best guess is the precise and purity of alloy and crystals, probably all nano. And quality and quantity of currents. Finding the right combination through extensive calculations and experiments. Correct proportions, angles and spacing. Pretty much everything but the basic design.
Gold and Fluid mercury is what I suspect.
Please let me share something from years of observation. First... from the atom up everything is electromagnetism. Everything is an electromagnet including ourselves. The true mass of our own selves can fit on the head of a pin and the balance is space.
Gravity = electromagnetism. Crystal Piezoelectricity influences included.
Go take a multimeter and put it on ANYTHING physical and you will get a reading in both A/C and DC. These are not there? These readings of anything crystalline or conductive do not exist from the ether it’s self?
It’s there... The needle moves when it should not by what we are taught...