I always used a small bell set and a snare drum to show the incoming band hopefuls. However I had tryouts on these instruments. I would play a simple short pattern on snare and have the kids try to echo me. I limited my numbers of percussionists. I would recruit my keyboard players by selecting those with piano backgrounds. Yes I knew I would have a "drum" section and a "keyboard" section, but they proved to be strong down the road. At last count I had 2 grads playing professionally in Nashville.