I made a rocket stove once out of cinder blocks - I didnt bring that when we moved...
SLIDE WARNING:
I was going to make one out of fire bricks like we used in our fire place, but could not find any in stock anywhere.
I did make one out of concrete blocks, but they aren’t really safety approved for use with fire, so we didn’t use it. Instead, I took it apart and used it to build a raised garden bed.