Now, if I can only find musket caps that don't cost more than a box of 9mm factory ammo!!
Back in my "BuckSkinner" days, I made a Tap-O-Cap for the #11's and not as pretty as store bought but they worked fine. I really see no reason why one could not be made for musket caps. As far as priming material, I'd start out with roll-caps although they are getting harder to find and the material has changed. I have used material in those kid's sidewalk poppers. They are hotter and I know they would work. !!! ...I doubt you'll see a store bought musket cap maker.