If, like me, you regularly need to defend your desktop against assaults from nefarious wine glasses and coke bottles, then the Pocket Artillery mini-cannon is for you. These CNC-machined blackpowder cannons have a stainless .177 caliber barrel and colored anodized aluminum base.
These cannons should be legal wherever blackpowder muzzleloading pistols are legal. The website is taking pre-orders for $29 or the equivalent in bitcoins
[ Many thanks to Craig for emailing me the link. ]