Trumpets take a lot of trial n error to find the right depth of cuts to get the sound your looking for. Keep a lot of notes, so you know exactly what depth you drilled each one out and what size drills you used. You have to drill them out in stages of different depths until you find what plays easy.
All I make are cane yelppers, but even with them you still need to learn what length to cut each piece, and how thin to make it.
WI Youth & LTH Mentor
Dodge Co. NWTF