d1 - Here we have 2 red wheels that spin in one direction and 2 brown spinning in the other. We need at least 4 Because 2 unbalanced wheels would make the apparatus spin horizontally.
d2 - Here I stuck the 4 wheels on 2 axles. The second is attached to the last boxed around the 3rd wheel.
d3 - No need for round wheels, we only spin a weight around an axle. The antigravity quantumfork therefor looks something like this. (We still call them unbalanced wheels to trick scientists.)