How long would it take for a heretek to build a servitor. Also, how hard would such a task be?

I'd probably rate it's time span the same as weapons, so 1d5 days, maybe 1d10 for really complex or high quality ones. I'd also adjust the modifiers based on what kind of servitor.

Servoskulls are easy. +0, or +10 even, if you ask me. Standard issue servitors, aka the human body on a tracked chassis style and it's ilk I'd say is maybe -10. Anything truly complex and nasty, like full on looks like human automata and terminator levels of competent Murder-servitors, I'd rate at -20 or -30.

However, this is just me extrapolating from what I've seen of the crafting rules, which I couldn't spot saying anything about servitors.

Also, obviously if the tech-user is making a servitor as in buying it as a minion, it takes dramatically appropriate amounts of time. Aka it happens whenever he gets a moment to breath and chill for a bit, and it's feasible he got the bitz.

Cool thanks. A player with a heretek wants to make a bunch of servitors to man the ship they got.