• a tube , cardboard ABS plastic, and bamboo all work
• heavy mono filament fishing line 80-100 lb test.
• 1'' wood screws
• small eye screws
• hard board
• 1x2'' or 3/4'' dowel
• drill with small drill bits
• hot glue gun
• fin toothed wood saw
The first step to making a tube zither is laying out the where the hole will be drilled so the string will be relatively straight.
We used a piece of wood to mark a ring around the tube about 1 1/2'' from the top and bottom of the tube.
Then we used a door jam to make four parallel line along the the length of the tube, we will drill holes at or near where the line cross the rings around the ends of the tube.
Next drill some pilot holes for your screws, we opted to put the wood screws in a straight line and the eye screws on an angle for a long low string and a shorter high string.
If you choose to use a soft material like cardboard hot glueing some backing plates (1'' squares of hardboard) inside the tube for the screws to screw into will prevent them from pulling through the tube material.
Add wood screws at one end of the zither and the eye screws at the other and tie the mono filament between them. Tie the mono filament to the eye screws before screwing them all the way in so the act of screwing them down will tighten the strings Finally, to make your zither playable add a bridge under each string made of a small piece of dowel or 1x2'' with a groove filed or sawed into it.
This instrument is very versatile and can be easily tuned to written musical scales, by tightening or loosening the strings or by moving the bridges around to change the effective string length. In our initial experiments we found that ABS actually works better than cardboard for the zither body producing a louder clearer sound. However, cardboard is a close second in terms of sound quality with the advantage of being easy to find. We assume using actual bamboo would produce the best results, but its potential to crack might not make it worth it.
Here's a video: