If you had a device, similar to a Stargate, but that allowed seamless two way transfer, and that could be moved (You could essentially strap a rocket on it, and fuel it from Earth), you could just leave it in orbit, and shove a satellite into orbit, or "anchor" the gate on a space shipyard, and funnel materials and components, and manpower, through it.
Let's say you want to build more traditional science fiction space ships (Crew quarters, command bridges, engines, science stations and scanners, the whole Star Trek-shebang), and you can't pass a whole one through the gate; the gate is too small, and making one big enough is cost prohibitive.
But just as you can have a micro gravity space shipyard in orbit around Earth, you could also have a low gravity launch facility and shipyard on the moon.
Would the low gravity of the moon, be of benefit to a large scale ship building program, or would it just be better to skip the middle staging ground, and build the ships already in orbit around Earth?
Assume that no artifical gravity technology exists (A rotating shipyard is acceptable), and that the presence of a new Stargate on a newly built ship means fuel reserves can be kept low until in orbit around the moon, and launch cost itself is therefore a minor benefit to keeping the construction in orbit.