I went a little crazy with paper cartridges and have tools from several manufacturers, all of which are satisfactory. I suppose making them myself wouldn't have been too much of a trick, but store-bought was cheap enough.
I did end up making my own boxes, in addition to several different store-bought versions.
View attachment 1150366
Boxes on the left are from "capandball" of YouTube, with homemade scrap wood versions on the right.
The funny thing is that I have been getting away from shooting cartridges. I don't particularly enjoy making them, and find that conicals perform poorly in game and are generally less accurate than round balls. The only real advantage for me is that they save time while shooting, which isn't really a bonus for me.