The original thing was designed to fit into a socket, with nothing more than the socket structure itself holding it in place. I wanted to create another type of holder, so I added a couple of 2mm dimples to the sphere.

This thing has 2mm dimples built into opposing sides of the sphere. Given the appropriate holder, you can hold onto these spheres using protrusions, and not just the friction fit of the socket.

Depending on the socket you put it in, you might get the best of both worlds. You could have a socket with protrusions in various fixed positions, which will snap into the dimples on this sphere.

At any rate, this derivative is just a tiny bit more functional than the last version.

1) Print a few of these
2) Slip them onto 5/16" rods
3) Snap them into the appropriate holder
4) Rejoice!