These are some rocket stoves I built last year. They work great and use very little wood, mainly sticks and twigs. The sizes all depend on the size pipe and cans you can find. You can build one with some tin snips a screw driver and a marking pen an awl or punch
Started with a welding rod can and a popcorn can for the first stove, then used an elbow and a short length of stove pipe for the second one. If you cut your can close you can get by without using j-b weld. I just used a couple small sheet metal screws. Small stove pipe is a lot easier.