Instrument-a-week (6): Froggy

Posted by on Apr 13, 2014 in Instrument-a-week, Music, News


Difficulty: 3 out of 5


  • a short tube with a diameter of about 40 – 50 mm and a length of 50-70 mm (easiest is if you use a cardboard tube, diameter 45 mm, used in post offices in Europe in rolls of stickers for envelopes),
  • cylindrical rod made of beech wood with a diameter of 8 – 10 mm, length 180 to 200 mm,
  • hard plastic sheet with a thickness of 0.5 mm (if you do not find a suitable piece of waste plastic, you can use the so-called “VIVAK” plastic sheet of the same thickness; you can get this in model makers shops),
  • piece of rosin, i.e. hard resinous substance that is rubbed on the bows of stringed instruments to add friction (sold in musical instrument shops),
  • fishing line with a thickness of 0.4 mm and a length of about 120 mm,
  • strong universal adhesive,
  • scissors,
  • utility knife,
  • lighter.


  1. From a sheet of plastic cut out a disk which has the same area as the hole in the tube. In the centre of the disk make a tiny hole, just big enough so that the fishing line can pass through it. Tie the line into a knot at one end in such a way that the knot cannot pass through the hole. Instrumen-a-week (6): Froggy, photo: Peter Kus
  2. Then glue the plastic disk onto the circumference of the pipe and allow time for the adhesive to dry.
  3. At about 15 mm from the end of the stick use a knife to cut a groove 2-3 mm deep around the entire circumference of the rod.
  4. Place a piece of rosin on a plate and melt it with a lighter. CAUTION: Take care you don’t burn your fingers!
  5. Immediately dip the rod into the melted rosin at the point where you cut the notch so that the notch is filled with rosin.Instrumen-a-week (6): Froggy, photo: Peter Kus
  6. Tie the line into a loop around the notch loosely enough to allow the stick inside the loop to be rotated but tight enough so that the loop does not slip out of the notch.

Play the little frog by rotating the rod around its axis between the fingers of one hand while covering the bottom outlet of the pipe with the other. You can change the croaking sound by extending your index finger to partially open the hole. You can also rotate the tube around the axis of the rod with the rod pointing upwards. The sound will then be similar to the croaking of a whole choir of frogs in a puddle! Instrumen-a-week (6): Froggy, photo: Peter KusThe sound is caused by the friction of the fishing line loop against the rod during rotation. Friction causes vibrations, which travel through the fishing line to the plastic circle that you glued to the tube. This acts as a membrane and amplifies the sound of the vibrations; thus we classify the instrument as a membranophone. Instrumen-a-week (6): Froggy, photo: Peter Kus

 © 2014 Peter Kus



(1) Membranophone
(2) Fruit-box Kalimba
(3) Moped
(4) Cardboard Tubophone
(5) Bird Whistle
(7) Water Flute