How do you tune a 16 string non-fretted bontempi zither model 66469?

To tune a 16-string non-fretted Bontempi Zither model 66469, use a chromatic tuner or tuning app to achieve the desired pitch for each string. Start by identifying the standard tuning for the zither, often in a diatonic scale, and then adjust each string by turning its corresponding tuning peg. Pluck each string gently while adjusting to ensure accurate pitch. Fine-tune as needed by making small adjustments and checking against the tuner again.