I'm going to try and recommend this one last time because I feel like I'm beating my head against a wall about this. EVEN BRONZE WOOL WILL CATCH FIRE AND YOU WILL GET A FLASHBACK! Why waste all your time trying something that has been proven time and time again to fail. The guys at Bruce Energetics have made a very good flashback arrestor for $6.95 each. Buy a couple, put them inline and stop thinking about flashbacks. Again, I have nothing to do with these guys other than thinking that they have a great product at a very good price. I you are that hell-bent on doing everything yourself, buy one and back engineer it to make your own. Who knows maybe you will save 99 cents or so on parts. Hardly worth the time and gas it takes looking for everything you need. Just ask my wife, I am the cheapest guy on the planet and even I bought a couple of them.
http://cgi.ebay.com/HHO-FLASHBACK-AR...item3a5844e494