How do I set a custom shape for multiple bones? I've tried finding a solution for this, but I can't seem to locate one.  Or perhaps I'm not asking the right questions.

Right now, I'm using Blender 2.79b, and what I want to do is to select multiple bones in an armature, and set the custom shape for all of them without having to do each bone one by one.

Mostly it's because I've got a model with ten fingers, and each finger has two control bones that should use the same custom shape, and I would rather not have to set the custom shape twenty times if there's a possibility to do it all in one go.

Any help would be greatly appreciated, thanks!
Make sure the Copy Attributes Menu addon is enabled (by default embedded with Blender).
Then select first the bone(s) that should receive the shape, then the bone that has the shape holding the Shift key > Ctrl-C > Copy Bone Shape