The file '20mm Sphere (Boilie) Roller (fishing Bait, Slingshot, Etc.) 3D Printer Model' is (stl) file type, size is 7.4KB.
I use 20mm balls for my slingshot ammo. I've made a few of these ball rollers to help me make my own slingshot ammo. So typically I use modeling clay. Roll a log of it a little bit bigger than 20mm in diameter, then put it in perpendicular to this ball roller, then I get 5 perfect little spheres each time.
You will need to print two of these and match them together.
The English use this exact same type of tool to roll "Boilies" which is basically dough bait for fishing. Using this tool you can get perfect-ish little spheres. So by all means you could use this to roll your own dough bait for fishing.
This can also be used by polymer clay artists to make perfect little sphere beads.
If there is interest, I may make this into a customizer so that you can designate the sphere size, number of tubes, and have it automagically generate a sphere roller for you.
I designed this in TinkerCAD. You can find the files here...
20mm_Boilie_Roller.stl | 38.0KB |