For Fragramatics types I use blue wrapped pressure wash hose which is thicker so it doesn't kink, much more resistant to rotting and cracking, and it won't mark a car's finish. I order all the components from Fragramatics except the hose itself. I have to "skive" off the outer layers of the hose on each end down to the metal. The hardest part is getting the tubing and wire through the hose, which I found the best way is to run a steel fish tape through the hose, attach the tubing/wire to the fish tape, then clamp the tape to something and pull the hose over the tubing/wire. I use mineral spirits as a lubricant by wetting a paper towel and wiping it over the tubing as I pull.
I started doing this after putting on a brand new fragrance gun and hose assembly and finding it badly kinked the next day. I get the blue wrapped hose from a local bearing supply, and it lasts about ten years.