This is my instrument, it's name is "Little B."  To make it you need three rubber bands, a small box, a ruler, and a clothespin.  First, you cut two holes in the box.  Second, you stick the ruler in the holes so only a little bit of the ruler is sticking out on one side.  Then you string the rubber bands on the ruler.  Finally, you put the clothespin on the top of the part of the ruler that sticks out the most.  My instrument makes lots of different pitches.  To make the pitch higher, you move the clothespin closer to the box.  Little B is in the string family.