This is my take on propane blower. It takes about 2 hours to make. The big tube is 2" nominal, the small is 1" nominal. The cone between is bought black metal "weld fitting" 2" to 1" and the end is the same thing but just 1" to 1 1/2". The air intake is regulated by flat round cap on piece of 10 mm screw. The jet is again 10 mm screw, which I drilled very nearly through with something like 6 mm hole along -on my lathe and then drilled one side at the end just 1 mm hole. Tunning is very primitive or nonexistent. It runs very well from 1 bar of pressure up, it really shines at 2 bars. That is about OK for 1" nominal I suppose. It has tendency to go off if the jet is badly positioned, the hole must go downstream. I think it could be also shorter, as it might actually have tendency to go supersonic. Should this be improved and to get different flame pattern I suppose custom end flare 1:12 will be needed. Jaro