Once you get a recipe chain to build something like super conductors, you can rake in the cash. Yesterday, in a few hours I made 120+ million units.
It seems that the gas you need is only sold on space stations from landing ships in wealthy systems.
The O2 + Compressed carbon trick worked wonderfully. To bad there isn’t a hopper system. It is still a very manual processes to load the refiners to multiply your compressed carbon. I suppose what I would want next from NMS is a min-mega factory system, that and diversified biomes on planets.