Building lighter rods out of heavy blanks
I was sitting here inspecting my most recent rod project when I got back to thinking about the "ultralight" rod I'd like to build, simultaneously thinking about how the 7 sections on this rod made it a real pain to line the guides up properly, and making all of the ferrule wraps was a pain, also. It ocurred to me that by taking a particularly long rod with two sections and only using the tip section, a one-piece light rod could be built, albeit it with a faster action relative to the rod were it to be employed as the manufacturer had intended.
Take a 2-piece 15' spey blank (gasp! All of you spey casters please forgive the blasphemy that I'm about to propose) rated for a 10/11, with a butt-diameter of 0.615, only use the tip section which should have a "butt diatmeter" of about 0.300 and a length of 7.5', and finish it as a normal rod. This corresponds with something between a 3-wt. and 5-wt. in many manufacturer's blanks, though it would take some testing to see what line weight best loads that blank. So in this fashion, it's possible to build a one-piece rod for a relatively light line. Were the blank a "low-end" moderate action, it would enable lighter lines to load the rod more easily, I would think.
A 3-piece blank of the same length and butt-diameter, and only use the top 1/3 section, creating a 5' blank with a 0.200 (approximately) "butt-diameter" for 1-3 weight lines.