Here's another tip for both mouth call makers and those that use them: the position of the cuts along the sound reed can make a big difference in the sound quality of a call, based on the calling techniques and mechanics of the user. When experimenting with call designs, a good method is to make the same call multiple times, but with the cuts located in different areas along the sound reed (upper, long reed). Some callers do much better with the cuts in the sound reed positioned nearer to one edge or the other of a call, rather than in the center.
Call users that are still trying to achieve their best quality sound can benefit by taking the time to learn where the best location of the cuts is for their calling technique. Having access to a mouth call maker that will make them calls with the cuts in different locations can be very beneficial to them.