Comment by rcxdude

There are many. At larger scales, weight and inertia dominate, but also magnetic fields matter much more than static electrical fields for generating force. At smaller scales viscosity, friction, and surface tension dominate, and electrostatics are much better at producing forces. Small-scale structures are often much 'stronger' than you would intuitively think (if you've heard the fact that ants can lift 50x their body weight, the square-cube law is why. A dog-sized ant would not be able to lift a car, or even breathe).

For this specifically, you would be looking at a radically different structural design, probably entirely flexural and without using traditional magnetic motors. Look at how MEMS design works in practice for an idea (though MEMS also tends to be constrained by current manufacturing techniques which push everything to be very planar).