You see the darndest things for sale/trade on the Internet

Homemade cannon for sale or trade

The Armslist, a website devoted to the buying, selling, and trading of firearms and related stuff, has this ad from a creative amateur gunmaker from metro-Detroit. The man (?) wants to sell his homemade cannon for $2,000 USD or trade it for a 1911-style pistol. Heh. I wonder where you would have to go in order to test fire it?