Okay, so here is the low poly together with the baked textures and normals. Polycount is 1600, most of which are used for the pipes, which seems to me like a lot of wasted triangles, but I'm not totally sure how to improve that. For some reason I get these orange reflections when I use the model ingame. Not sure what to do about that.
It is also appearent how much space on the texture map is wasted because there is no support for tangent space normal maps. Every pipe, wall and addon in principle shares the same texture and normals. Just because everything has to be rendered in object space, every single triangle needs a separate part of the texpage. So I'm not fully satisfied, for this reason I will try something simpler first. There are also some broken textures at the corners, which I will fix later.
I think I started with something too complicated for the beginning. I guess I will try something more simple and come back to this later. But I want to release it even in this state, just to prevent it from being wasted time and I'd still welcome every feedback you can give. License is GPLv2 inherited from the original.