double flaring tool

I got this set to do stainless lines on my Scout. 'Rigid' brand name. About 30 bucks as I recall. Works great.
View attachment 1715219899
Some of those work well enough. Thats the type my local parts store used to use. Most of the counter guys had picked up the knack for using it. If you go that route, try for a better one (like BD's), get extra line, and practice. The cu alloy stuff is now widely available again - a bit easier to work and won't rust like the steel lines.

I eventually broke down and bought a Imperial kit. A variety of kits have been offered over the years. Find a non-hydraulic one that does what you need.