I would say the 1/8" should be plenty, its really small gauge wire and I think the most bundled is 8 or so wires from the extruder. Maybe go to the 1/4" if you plan on keeping zip ties within it as well, but you may even be able to fit those in the 1/8". I would probably recommend though to go with a mesh cable wrap like this: . My makerbot came with it and it seems to keep the cables organizeby Ximfinity - General Mendel Topics