@Prime 2.0
Anyway, lets consider the potential of leaving behind an automated manufactory to make more manufactories. What would we need to make that happen? Well, we'd have to start by taking the Basic Automated Manufactories tech, for 175 RP. So, that there is most of an action. But wait! That tech specifically still requires CP, and cannot create installations:
So, we'd need to spend another research action or two, digging into techs that aren't even revealed yet. How much more RP will they cost? We have no idea! This one was 250 RP to start with, and Neablis has said that techs increase in price fairly rapidly as we go up the tech tree, so we can probably expect them to be 300+ each. And we need at least two more of them, to allow creating installations and to remove the CP requirement, which means probably at least another 600 RP right there. that's three more research actions, on top of the one for the first tech - in other words, an entire turn spent just researching stuff, without actually building anything, when again, *we could just be going back to Denva*.
Worse, there's the question of how much the new stations will cost and how productive they'll be. I fully expect they'll take a hit on both counts, which means we'll be spending even more BP to get less back. We could spend even more RP to correct that, but again, opportunity costs. We could be doing other stuff with that time, and the other stuff would just be better.
But okay, lets set all that aside and see about actually building the damn things. Currently, we can build deep space manufactories in this system for 375, or MS versions for 450. At that rate, it would take two actions for us to set up just the first automated manufactory - and if it ends up more expensive, then that's be even worse. Furthermore, there are chaos cultists here, so if we're gonna leave automated tech lying around, it probably needs to be scrapcode proof. That means it most likely needs a machine spirit, and ideally a psychic shield too - together, that probably means another extra build action or two to get the thing rolling.
Ah, but wait! We haven't even considered defending the thing from *physical* threats. If those chaos cultists manage to put together even a simple shuttle and swing by to start wrecking the things, then all our effort would go to waste. If dark eldar come by the system and decide to use our infra as target practice, then it would all go to waste. If Orks swing by to see what they can do with it, it'll probably do worse than go to waste. So that means we'd need to also put together some kind of defensive station - which probably means at least another 1000 BP, if not more.
But okay, once we did all that, what could we expct, soming back in 4-6 turns? Honestly, not that much. The basic DSM, without machine spirits or psy shields or any kind of automation, takes 3 actions to make a copy of itself. We have no idea how many actions it would get per turn, but based on the repair bay with fires once per turn, my guess is 1 to start with, and maybe more with more RP spent on automation techs. So if we left 1 behind, we could come back in 4 turns and have... 2 and 2/3rds of one. If we cam back in 6 turns, we could have, like, 4 and maybe most of a fifth. Really not very exciting. Add to that that all the extra expense and potential loss of BP from making the things automated, and I epxect we'd leave one and come back in six turns, and be lucky if there was so much as a second one waiting for us.
So, all in all, we're looking at at least two turns just to get the ball rolling here, in exchange for eventually coming back, and maybe having a second factory, or mayb having a pile of scrap because someone blew it all up. I'm sorry, but the idea is just bad, and we shouldn't do it.
And if you suggest leaving behind tech priests as well... Well, that has all the same problems, except now we also need to provide them life support, and defenses, and whatever other tools they need to do their job, and also it costs us RP, and maybe it upsets the tech priests who didn't sign up for this, and again there's a good chance they all just get enslaved by dark eldar, or that someone manages to torture out tech secrets out of them... Again, I'm sorry, but this is just a bad idea. We shouldn't do it.