There is no great mystery to this, just fold the metal over to trap the mandrel inside, then beat on it, heating the brass from time to time to soften it again, and gradually work the brass around the difficult point. If you do this, you will ruin more than two for every one which might be considered good enough. Well, at least I did. Each one will take you about 4 hours to get to the stage you see in the middle of the picture below. Not counting the failures which end up flying across the room in disgust. The scabbard on the right is almost finished...that is, it has been soldered, shaped, sanded, and rough polished. I once had a scabbard fail on me during the rough polishing, but that was my fault...I had inadvertently allowed the metal to become too hot under the buffing wheel, melting the solder. From our mistakes we learn....grin!
Above are four of the better ones. The surface of the top scabbard shows fire scale. Thats the mark left by the torch that I used to soften the metal.
Above is another angle of the same scene. This time I flopped the right hand scabbard to show the underside. Yup, still lots of polishing to do yet! Its not like auto body work where you can just slather in a little body putty and paint over the defects, here all the defects show. Its sort of a case where we need to decide when to stop seeking perfection....the client won't pay for that search! Mind you, I give as good as I am capable of, and every scabbard is (I hope) a little better than the last one.