I've been after a cobza / koboz for years; a mate made me a surrogate koboz with a flat back, fretless finger board & four concordant double courses which sounds about right, but doesn't look the part in the slightest. Various Hungarian bands have used them over the years - Makvirag for one, but my favoite player is Hungarian lutenist Andras Kecskes, who used one throughout the Clemencic Consort's landmark medieval albums of the 70s.   

Still looking!