I had an idea for a rain stick and it turned into an instrument that more simulates ocean waves with each flip.   After a little trail and error, I present to you the Wave Maker.  The lid prints in a separate part, and then is glued into place.  I printed this out of petg with a .6mm nozzle, which took just under 4 hours on my mk3.  The Wave Maker is 7.5 inches tall x 3 inches wide.  I designed the internal components to be printed with no support needed.  This model also has zero overhangs which should make it easy for everyone to print.  I also used gorilla glue and it seems to be holding well.    .177 caliber bb's. scaling this print will affect its functionality. 

EDIT

After some more testing, I enlarged the model by a half inch changed the positioning of the wave makers inside