Problems with my combustion chamber

I recently built a rocket stove out of a 55 gal drum. I do not have the welding materials to fit my pipes together and getting the elbow for the stove pipe is out of my budget for the project. What I am using is a ammo can as my elbow. The can is laid on its side and the pipes enter from the side and tope. This setup up works perfectly and is easy to disassemble. My problem now is that I want to make a smaller version out of a 5 gallon container but the ammo can idea won't fit inside. Any ideas would be greatly appreciated. Again welding is just out of the picture for me at this time.

Cut the pipes to a near fit with some tabs left for an overlap. Pop rivet the tabs. Bed the pipes in a clay/pearlite or clay/sawdust mix or similar. Apart from being a former, you don't need pipes at all, you could do it with cardboard tubes then burn them out.