Rainstick

In many cultures, summoning rain often included the use of musical instruments.
One well-known example is a rainstick, an instrument that mimics the sound of rain.
They are traditionally made from dead cactus tubes with cactus spines hammered to the inside and filled with tiny pebbles.
When the stick is upended, the pebbles fall to the other end of the tube, making a sound reminiscent of rain falling.

Picture are for reference only. This instrument is sold individually.