Wikipedia
The kashaka is a simple percussion instrument consisting of two small gourds filled with beans (essentially, two small maracas connected by a string.) One gourd is held in the hand and the other is quickly swung from side to side around the hand, creating a "clack" sound upon impact. It originated in West Africa, but has been reproduced in various countries under different names: Patica (Japan), Kosika (USA). Other names include Asalato, Kes Kes, Tchangot Tche, and many others.
Kashakas create both shaking sounds and percussive clicks by swinging the balls around the hand, making them hit each other. Learning to catch the Kashaka can be difficult at first but this enables a much larger variety of rhythms to be created. Also, as players' hands come in different sizes, it is important to play a Kashaka of the right size, as it makes learning how to play and master different rhythms much easier. When a Kashaka is played in each hand by an experienced player, polymeters can be produced by playing two different rhythms with different time signatures.
Kashakas are considered a toy by some, and a percussion instrument by most. They are also a skill-development tool that can help improve dexterity, ambidexterity, brain hemispheric synchronization, and develop the ability to multitask. It can also build muscle mass and improve flexibility in the hands, arms, shoulders and chest. It is also considered a meditative tool that can create a trance state, promote relaxation and lower stress levels.