Just to be clear, what people are referring to as a "splitter" or "manifold" is, essentially, a tee with the gas from the cylinder coming in at one port, and leaving through the other two ports, with a needle valve at each of those ports. Want a third port? Add another tee and valve. It doesn't matter what it looks like from a practical perspective - if there are 3 or 10 openings, one of them is the inlet, and all the others are outlets, with the same pressure at each outlet, no matter where it is. It's probably easier to buy a prebuilt manifold, but it might be cheaper to buy the pieces individually and put them together, depending on what you're looking for. Either way, it's nice to know exactly how it works.