The amount of water in the cup will affect the pitch. This is quite troublesome to do, so you have to experiment slowly. First, take out a dozen cups (preferably the same, the more cups, the wider the range of the sound, 88 of them will be a piano. Of course, the cups cannot make too high or too low a sound) and take a dropper (you can finely adjust the amount of water) ), then slowly add and subtract water until you can arrange a pitch of about two octaves. It would be nice to just be able to hear the melody without having to fix the pitch. Then after you are familiar with the sound represented by each cup, you can play it with a stick.