Practice Lap Harp or Zither

Did a reverse image search to figure out what this instrument is called. It has 15 strings and a guide imposed on the surface that indicates the note each string is supposed to be tuned to. Unlike other lap harps I saw pictures of online, this one does not have a hole in it for acoustics. There's nothing on it that indicates a brand or year. Any ideas on the worth would be greatly appreciated! Thank you for your time.