how can I make or bye a deep sounding train or airhorn
Marine supply store, West Marine, etc.
Check out the nearest PETERBILT/ Freightliner/ Volvo Dealership By the way Buy is spelled like this...Bye is like See Ya! (LOL)
Majority of these can be found at car dealerships and auto stores; hence, your best bet will be to check for such stores in your locality and purchase one, because making one can be very tricky. You can also check in online websites such as http://www.streetbeatcustoms.com/Chevy/Silverado/Accessories/Air-Horns/.