PVC membrane air horns are not that hard to build.
It is basically a membrane slapping on the end of a pipe
https://www.youtube.com/watch?v=1Zl32BW0qmg
https://www.youtube.com/watch?v=4e60A0UrvJA
https://www.youtube.com/watch?v=LbleT_vZrzE
I one built a 4" x 6' which was in the ship horn class
A PVC membrane air horn are not that hard to build.
It is basically a membrane slapping on the end of a pipe
https://www.youtube.com/watch?v=1Zl32BW0qmg
https://www.youtube.com/watch?v=4e60A0UrvJA
https://www.youtube.com/watch?v=LbleT_vZrzE
I one built a 4" x 6' which was in the ship horn class
A PVC membrane air horn are not that hard to build.
It is basically a membrane slapping on the end of a pipe
https://www.youtube.com/watch?v=1Zl32BW0qmg
https://www.youtube.com/watch?v=4e60A0UrvJA
https://www.youtube.com/watch?v=LbleT_vZrzE
I one built a 4" x 6' which was in the ship horn class