Its an adjustable CW:
It´s a hollow light weight plastic chess piece, I made a hole on it an passed string through it in order to attach it to a yoyo string. The interesting part about it is that you cant adjust the weight to what ever you want it to be. To do so just enter the desired amounts of clay into the chess piece until you got the disired weight.
This one isn´t my idea I saw a tuturial on instructable on how to make this CW, I think they´re called wasp nest or something like that. So I desided to make one.