PVC train horn

Main Train Horns
1

I know their was another tread similar to this, but i really want to make one of those pvc train horns you see on you tube, i plan to put some on my car.

They dont look to difficult to build but i dont know how the internals of the horn work, so could some one explain how the internals of a pvc horn would work, or better yet could someone post some plans?

Thanks:D

2

http://en.wikipedia.org/wiki/Train_horn

3

Could someone post a pic/drawing of what the inside of a pvc diaphram looks like?
Thanks

4

there’s a guy on ebay that sells plans.