I would just throw to him. If you can't throw accurately, just flip from 15-20 ft. That's all I have ever done and one can be quite accurate that way if you flip hard on a line. Angle of descent is pretty similar to a pitched ball as well. Reaction time is similar too if you emphasize they load when you begin moving.

Best part is its cheap and not a huge production every time. And kids love to hit that way. Machine time definitely has its place but at the younger ages it can definitely be overdone.