Bonding should be by the widest practical means. Wide cable tray is effective when it is made of zinc plated steel and carefully bonded at the ends to control panel and motor frame. Zinc plated sheet steel channel is also effective. The fact that the width is folded into a U shape does not matter. A closing lid helps. Solid steel conduit bonded at both ends is effective. The spiral construction of flexible conduit makes it less attractive for RF shielding because the spiral shape forms an inductor, even with partially shorted turns.
Suppose we bend our wire into a squarish, U-shaped loop so there are effectively two parallel wires running through the magnetic field. One of them takes the electric current away from us through the wire and the other one brings the current back again. Because the current flows in opposite directions in the wires, Fleming Left-Hand Rule tells us the two wires will move in opposite directions. In other words, when we switch on the electricity, one of the wires will move upward and the other will move downward.
A simple, experimental motor such as this is not capable of making much power. We can increase the turning force (or torque) that the motor can create in three ways: either we can have a more powerful permanent magnet, or we can increase the electric current flowing through the wire, or we can make the coil so it has many "turns" (loops) of very thin wire instead of one "turn" of thick wire. In practice, a motor also has the permanent magnet curved in a circular shape so it almost touches the coil of wire that rotates inside it. The closer together the magnet and the coil, the greater the force the motor can produce.
Here is where metallurgy comes into play. A motor rich in magnetically soft material will be more efficient, producing more work with less heat. And since the magnetic capacity of a motor also is influenced by the amount of active material (more core, more laminations), the tendency might be to try to add as much magnetically soft material to your design as possible.