Are the links on the Wiki broken? Im trying to find a how to for making a tennis ball combustion canon or mortar but am struggling to find something. I am newbie and pretty lost at where to start.Im looking for something to fire off for my Dog and something I can have fun with

Im a complete noobie and ive tried looking around and cant find something in good detail about how to make something.I tried looking through the wiki but I think the links are broken. I am looking for a mortar or a gun to launch tennis balls for my dog but I want it to be able to go far and im just ...