If you make it a question, you'd best be off reading the critique guidelines, that ensure your Q is focused on a certain aspect you want to improve, and is thus possibly answered with an objectively 'correct' answer.
well, it is a diagram, but I'd like to create a version with a larger domain. It will have a large free area in the bottom right that would be good for placing tables with exact values. So it's also a table question (which font to pick, for example)
@joojaa well, the choice of tools is not my actual concern here. My plan is to create a diagram with larger domain, which will have a large unused area in the lower right corner. I'd fill it with steam tables
well, I'm not sure if I like the idea. It's true that following iso-lines can be hard with the current way they are done, and that a visual aid might be helpful. otoh, stepping back from the diagram should make it look like a zebra
yeah, thing is the big size changes things so thin lines themselves will look weird. And engineering drawings ARE artworks and should eb considered such, you have quite significant leeway in making them, we are nolonger in the 1960's and using plotters only you know.