I have no use for a shot maker since I rarely load lead shot loads and am mainly a slug, buck, & ball guy and when I do load shot loads it's usually non-toxic shot. Thus I hardly know what a shot maker looks like.
On the sabot and bullet size thing; some people size down jacketed bullets with the Lee push through sizer dies so if you end up needing to make 0.445" diameter bullets or something like that a push through sizing die on a sturdy reloading press would be the way to go. I've heard that case sizing lube should be used on the outside of the bullets when doing something like this and probably should be cleaned back off before being loaded in the sabot. I might even be tempted to look at making a sizing die out of a length of 45-cal barrel liner from Track of the Wolf which would leave the main diameter of the bullet the same but the bullet would come out the top of the die with rifling grooves swaged into the side of it which would do double duty to both decrease the average diameter of the bullet and give it a spline like outer surface to tightly grab and engage the sabot. Wouldn't hurt anything as far as accuracy since when fired from a normal gun a bullet comes out the end of the barrel with such rifling grooves in it. It just all depends on how far one wants to take this.