Tried to modify medium squeezer set to fit slightly recessed rivet heads along cowling. First attempt was imperfect because the set already had one flat side, so it was difficult to regrind to a round shape. The finished set didn't work very well; left flaws on the manufactured rivet head. Tried unsuccesfully to fabricated a small cylinder out of mild steel stock. Finally chose to grind down one of the larger diameter sets to a proper size. This works well.