Large rubber bands
Cardboard (could be from an empty cereal box or any kind of large box)
Scissors & tape
1. Cut a hole out in the top of the box.
2. Ease 5 rubber bands over box so they are covering the hole (large sturdy rubber bands are best for this)
3. Cut a section of cardboard for the fret and tape it on the back of the box.
4. It works (well, kind of)!