Nitrous plumbing A1A...??..

Heres a few tricks i use.

Take a section of hard line and mark it every inch. Now put tour bender dead on one of the marks and make a 90 degree bend.
This tells you how far after the mark the tube starts bending.(not all benders start bending right away.) It also tells you how much line a certain radius uses.

These same tricks also work when building cages.

So if your first line goes 3" then bends just make the nwxt one 4" then bend and you end up with nice matching lines. It also helps you measure out the length of raw (un bent) tube.