best way to build interplanetary vessels on the moon is in sections, launch and assemble them in orbit.
best way to launch sections: electromagnetic mass-driver
bonus: that same mass-driver could easily be used to lob large rocks at terrestrial enemies. boom, with no radiation... and, if done cleverly, with quite a bit of plausible deniability.
let us go back to the moon, please.
do you really want to imagine a world without velcro?
MORE FUNDING FOR SPACE EXPLORATION NOW!!!!
Sounds like the outline of Heinlein's book, "The Moon is a Harsh Mistress".