Not what the cube means. The cube represents the physical dimension the circuit will grow in, the number assigned is the rate it grows at. An adder with more logic stages must be longer... because it has more logic stages. An adder with greater fanout must be wider because the traces need to be widened in order to lower their transfer resistance (and thus Beat Generation and dissipation). The ones with more wire crossings must be taller because wire crossing is done by vertically tracing into the next level up in order to jump over the wire(s) it must cross. Speed is basically in the L direction, power consumption is mostly in the f direction, and while the t direction also has a lot of effect on power, t mainly indicates the cost, complexity, and construction time of the design.
Fanout describes the maximum number of inputs that are attached to the output of one logic gate (how many gates share the same wire). If we were to randomly say that each gate consumes three Watts of power, your source gate must be able to maintain 3fW min without melting. This means for each gate you add into the fanout, you have to make this source and wire that much bigger. This is not a problem in Minecraft.
With that in mind, look at the Stalinsky adder, paying special attention to it's traces. Look at an insa-carry adder. Tell me what you see.
Fanout describes the maximum number of inputs that are attached to the output of one logic gate (how many gates share the same wire). If we were to randomly say that each gate consumes three Watts of power, your source gate must be able to maintain 3fW min without melting. This means for each gate you add into the fanout, you have to make this source and wire that much bigger. This is not a problem in Minecraft.
With that in mind, look at the Stalinsky adder, paying special attention to it's traces. Look at an insa-carry adder. Tell me what you see.