I made a ball starter out of three pieces of dowell. One around 1 " in diameter and the other two probably 3/8 of an inch. The smaller diameter pieces stuck out of the larger one at right angles to it and each other. So you could just start the ball with the end of the big piece or drive it in 1" or 3" with one of the others.
I also took a flat piece of of hard wood and drilled two holes in it - a little over 1/2 inch in diameter. After some sanding and smoothing I could put a ball and a greased patch in both and press them out and directly into the muzzle with the ball starter.
Both had leather thongs so I could hang them from something I was wearing. They worked pretty good on the range. I've never had to fire a follow up shot from the .50 caliber Hawken I made them for.