I am wanting to use the Butt/handle section of one rod with the top section of another. For reference the handle section is from a Missing at Sea 8’ Pe 8 popping rod and the top section is from a 8’ Smith Off Shore Stick. The issue I have is the the female ferrule on the handle section is a slightly larger diameter than the male ferrule of the top section.
My idea is to put a layer / coat of epoxy on the inside of the female ferrule and then carefully ream it out until it is the correct size. I had though about building up the male ferrule but, would rather not modify the smith top half as I still have the handle section for it. The reason for mating the two different parts would be to gain a longer handle/butt section.
Has anyone done this or have any suggestions as to how to do it?

You would be better off in reducing the size of the female section by finding a glass section that will fit well over the male spigot and then sleeving the inside of the female portion. The female portion should not have any taper so it can likely be sleeved from the top end rather than having to go through the butt of the rod. Because these were tip-into-butt ferrules there is not likely to be much, if any, taper on the spigot portions. This simplifies things in one way but could cause some slightly difficulty in finding a glass sleeve that fits well over the male spigot. Most scrap pieces of glass or graphite rod scraps are going to have some taper to them, unless you source them from a rod's lower most butt section.

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Thanks for the suggestion. Making a sleeve for the male side is what I originally thought I would do. The problem is that the difference in diameter is only 1.2 millimeters. I have the male spigot from the butt section that I want to use and was originally going to open it up to use a a sleeve for the spigot of the new top section. The difference in size is close enough that finding something with thin enough wall is proving to be difficult. I did experiment with another butt section but, it tapers so the end of the male spigot moves around at the bottom once inserted. That’s when I had the idea of putting a coat of epoxy on the inner diameter of the female side to build up the area that is tapered.
Thanks again for the ideas and suggestions