I have been looking at pictures of rocket for a while and this summer built a couple of simple ones. A larger one we used for cooking beets before canning. Kind of fun to experiment with and a good way to use up some of the twigs that have fallen in the yard from the high winds this year.
I even had to make a pot of coffee. I am going to make more permanent ones. We like to do as much of our canning outdoors as we can to keep from heating up the house. We have propane cookers also, but this is good to have just in case.