I seem to answer this question once or twice a month, so I asked the powers that be to pin this for us. If I'm not clear, ask the question.
I like blown burners, they are brute force and dirt simple (just like me), so if you are looking for venturi advice, you must needs go elsewhere.
Building and operating a burner like the one described below is dangerous. It can burn you (since hot is what it does). It can create explosions of various sizes. You are responsible