This is a good game, somewhat reminiscent of Cell Machine and the Cellua mod.
Adding units is a great idea. You can create a huge circuit in them, but the circuit will be 1 block in size. (Almost like in real life, where a circuit with a huge number of elements can be the size of a fingernail)
But I found a bug: if you delete the head from the extended piston, the piston will simply disappear without adding it to the inventory.