Welcome, Rob! Don't need to tell you to have fun with this! Sounds like you already are...we all look for suitable projectiles, and you can find an amazing assortment of "stuff" to shoot, (keeping in mind to always be safe!) The other thing we all end up looking for is material that will make cannons, howitzers, or mortars. When doing so, remember the safety rule always repeated by Double D, and all the rest of us...wall thickness has to be equal to bore diameter. So, a three inch diameter rod could be bored out to one inch, ect. And don't forget the base, same plan there! BoomLover