The Marimba is the huge xylophone type instrument that is often shared between several players at the same time. Usually one of the musicians has the scrapey wooden thing (Comment if you know the name, maraca?) and wanders round collecting tips. Then they carry the whole shebang somewhere else and start playing plinky plunky versions of classics like Cielito Lindo and La Bamba. *edit* Nope, they’re not maracas. Google turned up this page on how to make your own marimba though, happy hammering!