You can build a tuned PVC pipe instrument for a few dollars: cut 1.5-inch PVC pipe to the lengths below, slap the open ends with a flip-flop or foam paddle, and you get a deep, punchy C major scale. Cut each pipe a little long, then trim to tune with a tuner app.
This is the same idea behind the viral “PVC pipe orchestra” and slapaphone videos.
What you need
- About 4 m (13 ft) of 1.5-inch PVC pipe (Schedule 40)
- A PVC pipe cutter or fine-tooth hacksaw
- Sandpaper or a deburring tool
- A tape measure and marker
- A tuner app on your phone
- A paddle: an old flip-flop, ping-pong paddle covered in foam, or a purpose-made paddle
- Optional: pipe clamps, a wooden frame or a rack to hold the pipes
PVC pipe cutters · chromatic tuners
Pipe lengths for a C major scale (C3 to C4)
| Note | Frequency (Hz) | Length (cm) | Length (in) |
|---|---|---|---|
| C3 | 130.81 | 64.3 | 25.3 |
| D3 | 146.83 | 57.2 | 22.5 |
| E3 | 164.81 | 50.8 | 20.0 |
| F3 | 174.61 | 47.9 | 18.9 |
| G3 | 196.00 | 42.5 | 16.7 |
| A3 | 220.00 | 37.7 | 14.8 |
| B3 | 246.94 | 33.5 | 13.2 |
| C4 | 261.63 | 31.5 | 12.4 |
Lengths are calculated for 1.5-inch Schedule 40 pipe at about 20°C, slapped at one open end. Real pipes vary, so add 2–3 cm to each cut and trim down.
The maths, if you want to change notes
When you slap a pipe, the paddle briefly closes that end, so the pipe acts like a tube closed at one end. Its length is roughly:
Length = speed of sound ÷ (4 × frequency) − 0.6 × pipe radius
Use 343 m/s for the speed of sound at room temperature. For 1.5-inch pipe the inner radius is about 2 cm, so subtract about 1.2 cm. Longer pipes give lower notes; halving a length raises the note by about an octave.
Step by step
- Mark and cut each pipe 2–3 cm longer than the table length.
- Deburr and sand the ends so they are smooth and safe to slap.
- Tune: slap one end with the paddle while the tuner listens. If the note is flat (too low), trim 2–3 mm and test again. If you cut too much, use that pipe for the next note up.
- Label each pipe with its note.
- Mount the pipes side by side, longest to shortest, in a frame or with clamps, with the open ends facing you at a comfortable height.
Playing tips
- Slap flat and quickly so the paddle seals the opening for an instant, then lifts away.
- A softer paddle gives a rounder tone; a harder one gives more attack.
- Try simple tunes such as “Ode to Joy”: E E F G G F E D C C D E E D D, using the same note names as our kalimba tabs.
Upgrades
- Add sharps and flats for a chromatic set.
- Use wider pipe for deeper, louder bass notes; recalculate lengths with the larger radius.
- Add 90° elbows to fold very long bass pipes into a compact frame.
Safety
Cut in a well-ventilated space, wear eye protection when sawing, and sand all edges. Supervise children with saws and cutters.
More DIY ideas: instruments from waste materials and homemade instruments for adults. Curious about the pro version? Read what is a slapaphone.
