yeah I tried that but it also has a level of transparency and glow(?) to it, that I cant seem to easily recreate. Actually I did once but I was messing with it for so long I don't even remember how I did it. It also seems to use two different shades of blue one for the internal parts and a normal dark blue for the walls.
I mean here's an ok one,

then a bad one.

And even my best versions don't look right. So I want to go over them all at the same time now and set em up properly, which I feel there must be some simple "recipe" I'm missing. But I just cant figure it out.