If you choose to use steel line, the common Brake/Fuel line is what is plentiful.
I noticed Auto zone is using a dark coated line now, it appears to be a polymer coated instead of galvanized/zinc.
Prolly because of environmental reasons.
I find a ball bat works well in a vice for making various radius, just pull the line tightly against the bat, as you are bending it.
It makes those fancy flex coils that are usually used near the master cylinder on vehicles.
I have various size tube benders but they are pricey for a person who uses them infrequently.
