why can i get the air gun

Which one Chicken gun, Soda Pop gun, Shrimp gun, etc?

But I'm pretty sure Jamie made most of the air gun/canons.

Sorry but our mind reading skills are rusty. It would make more sense if you actually gave more relevant information. There was more than one air gun used in show. It's the equivalent of asking what the car was they used in show. Please try and use some common sense.

I'll glad to build you one if you a) tell me which one; b) cough up a lot of money and c) sign a waiver so huge it will need to go by freight.

Or you can pay attention to the many episodes where Jamie and Grant explain how they build them