Reel seat magnets
There are a number of things that set a custom made fly rod apart from factory rods. One nice addition I saw on renoun builder Chris Barclay's rods is to add a rare earth magnet to the inside of the end cap (simply epoxy it in place). Then when changing leaders or adding tippet you simply cut off your fly, touch it to the end cap (where it is held by the magnet inside), change out the rig, and then grab the fly and tie it back on.
For those of you who sell rod adding an inexpensive magnet is a great way to stand out from the crowd.