Updated: see new version info at the end
This customizable thing is for holding the top and bottom pieces of a two-piece fishing rod together during travel and storage. I've used rubber bands, Velcro, and just left the two pieces free and haven't been really satisfied.
I based the design off of thing 1753721 by jcox10 -- 2 piece fishing rod holder clips. That design was only for a specific rod though. I made a model in openSCAD that can be customized for any rod. You can choose the two rod section diameters, the wall thickness, the distance between the rod sections, and the height of the clip.
I've included 4 different clips that I made as STL files. The numbers are the diameter of the rod section in millimeters. So Rod Clip_6_6p5.stl is a clip with diameters of 6mm and 6.5mm.
For very small rod diameters it can be very difficult to get the rod tip to snap into the clip, so I tried printing the clips in flexible filament. The problem was that the angle of the cutout was too large and the rod tip would slip out.
To fix this I updated the openSCAD model to allow you to change the size of the cutout. The old model cut out 90 degrees out of the 360 degrees of the circle. This new model allows you to specify an angle to cut out. I found for flexible filament that 60 degrees works pretty well.
The flexible filament works so well that I've gone back and reprinted all my clips in it.
If you don't have flexible filament you could also change the cutout angle from 90 to 100 or more degrees to make it easier to pop the rod tip in and out.
I made mine out of ABS because this is going to see sunlight, cold, water, etc. and ABS is supposedly more weather resistant. That said PLA would probably work fine.
With ABS I find using a brim helps keep the parts from warping. I choose 50% infill, but it would probably work with less fill -- it depends on how stiff you want the clips.
I found for my printer, that adding .2 to .3mm to the diameter of the rod sections fit best, but your printer may be calibrated differently.
These clips work really well with flexible filament as long as you change the cutout angle in the customizer to 60 instead of 90 degrees.
I find that flexible filament sticks just about the right amount to blue painters tape at 50C with no brim.