Fly Rod 6wt 9ft — Designing the Grip in Tinkercad
A little groundwork needs to be done before heading to the design table.
You need to measure the blank butt — the thickest part of the blank. That tells us how big to make the hole through the handle for the blank. On the blank I'm working with, the thickness was 9.45mm. I've roughly rounded this up to the next full millimeter, so into the notebook goes 10mm for the blank hole. Foam filament expands somewhat during printing, so it's good to leave a little wiggle room. And you won't need any sanding afterwards if you can dial in the print settings so the hole isn't full of bulging fuzz. I want the handle to sit straight and tight against the blank, so no filler is needed. I'm making a straight-diameter hole, even though the blank tapers toward the tip. No point fussing with a tapered hole when a properly sized straight one fits tight anyway.

Then measure three points on the reel seat too. I'm putting single-handed threads on these facing toward the blank butt, and partially embedding the top of the reel seat inside the handle. You can see from the photos what to measure — three measurements from the reel seat into the notebook. Then you can head over to Tinkercad and start tinkering.



The first video is a bit longer, but it covers basically everything you need to use Tinkercad. Anyone can make exactly the handle they want.
In this second video we also design a butt for the end of the rod.