I made my first ones in 1977 ..or thereabouts.
It's not hard, several advantages....
Exact length ... no inch longer or inch shorter than would ideal.
If at one point in time , you want a shorter line, you can make it out of a longer one. Or change a straight end to a 45 or 90...vs buying another line . and waiting for it to arrive.
Did I mention I hate banjo ends, and crimped fitting lines.. and double hate a double banjo line...
And don't even get me started on a U shaped line going over the front fender from one calibre to the next.. looks like tractor plumbing.. ...
So yeah . Build your own..get exactly what you want..