The problem is: how do we get rid of that painful area on our upper lip? One solution among trumpeters is — though guys feel no pain. Another solution is the Herbert Clarke mouthpiece (BRASS BULLETIN no 20, pp. 27-28); I copied it but it did not work; it was much too comfortable for my lower lip, which did not need help.
What I now do is this. I make an incision with a jigsaw in the outer wall of the mouthpiece rim about 2 mm (no more) below the highest point of the rim surface. I continue until the incision reaches round one third of the rim circumference. Then I take a piece of hard round wood (a pole with a 1’’ diameter) and hold it on top of the mouthpiece rim. One or two blows with a hammer are enough to create a slight depression in the rim surface. It is less than 1 mm but our sensitive upper lip will feel less pain and have more endurance. We now have only to solder what is left of the hole (use lead-free solder) — but chewing-gum or glue also work. Now you can use a medium rim with a good bite to its full advantage, with more endurance and better high notes. It takes some experimentation — and a few mouthpieces! — before you get the best result.