Is it possible to just add ProductionUpdate module to a building that does not normally produce units[like tech buildings] and produce units out of it?

Or does door anims need to be added too?

It should be possible. I did it once to a civilian building to make it produce the us drones. They just flew up from the centre.

---

Will try it out. So a unit can produce units too I guess...

Pretty much.
ProductionUpdate makes it so that the object can make production queues and are able to start progress producing something that requires cash. It's not limited to producing units, but also for upgrades, check out how America drones work and Overlord attachments as well as any tech building.

---