Have a fly fisherman son. Want a water green blank with a nice BRIGHT ORANGE THREAD THROUGH IT. Just a single thread that appears similar to a fly line cast upon the water.
It wouldn't be hard to do so long as you have a way to position the line. In tube casting would be the way to go so you can control the depth and appearance of the materials.
Charles if you have a green blank you like you could tube it and turn it down, CA the line to it and then build up a CA finish to cover it. You are pretty good at CA finishes as I recall.
I may try on the blank cutoff to engrave a groove with my Dremel tool. Then fill it in with orange to simulate the fly line. My only reservations that this is on the surface and there is nothing to protect it from chipping out.
Experiment as the CA might cause the thread to disappear. Rod building requires a color preserver in many cases to keep the thread from becoming translucent or transparent. Some builders use white thread- the thread disappears when the epoxy is applied.