I'm searching for a very special instrument , it is somewhat a (wooden?) box with metal strings , with the longest being in the middle and then getting shorter towards both sides.
You play it by rubbing your fingers onto the strings.

Any idea?
Quote by dmakeev99
No , not the Zither.
I made a sketch (looks bad) : http://imgur.com/sBzHmd0
The strings are rather thick , metal strings.
Also the box is rather small.
It looks like a thumb piano, or m'bira (aka kalimba) - but that has metal tines, not strings:
There's no such thing; there never was. Where I am going you cannot follow me now.