Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:4064853.
I designed this to allow me to attach a Christmas ball to my Eggbot in something like a three jaw chuck. It works great to hold and center the ball just by gripping the end.
I've included the SCAD file if you need to adjust the sizing for whatever you want to attach. A bit of adjustments and this could print without supports.