Years ago, I had a caller that was a piece of 1/2-13 threaded nylon all thread that was screwed into a wooden handle and on a lanyard, a piece of nylon 1/8” x 1/2” x 2” long that you slowly clicked down over the thread to make a sound they make when breaking acorns or nut hulls. Wish I could find it.
I recently heard about keeping to half dollar coins in your pocket. You use it in two different ways. 1. Hold one coin in your one hand with thumb and index finger tightly around its edge and the rest of that hand in a funnel shape. Then with the other coin, with the edge, tap it against the other coon to make an alerting sound. 2. Holding faces of coin between thumb and a finger or two, you use the edge of the other coin in your other hand to slowly click it on the edge serrations to make a clicking sound like nuts and acorns being chewed.