I thought I put a comment on it, but it doesn't seem to have stuck... Anyways, I'm going to make something almost identical to this very soon I hope. I have a cue ball in the mail and I'm going to turn the centre band on a lathe, use an endmill to flatten the circle and put in a metal "button" (just as you have). Then, I'm going to drill and tap a 13mm x .75 (I believe) hole in the bottom and make a shift knob for my car out of it
I hope mine turns out looking as good as yours when it's done