In high school metal shop I made a completely accurate 1/8th scale Army Cannon based on blue prints I found from the 1870s. My instructor was none to happy when he found out that it was fully functional. In wood shop I made the cart for it. It'd shoot a tennis ball a long freaking ways. Or not very far at all if you loaded to much smokeless behind it. Estes rocket motor igniters are how we fired it off.