Be very afraid link to the Something Awful forum where Roland Tower has made a flame thrower from everyday parts available from a B&Q. The only thing stopping throwing a flame in a similar manner to a military grade device is that it uses too light a fuel. The fuel is usually mixed with ingredients to make more effective. This means added ingredients that have a heavier sticky base (though a quick trip to the kitchen or returning to B&Q would probably do the trick).
it would only take about five minutes thinking about alternative materials for the fuel and device to have a dummy’s guide to making a military grade flame thrower. And that is a terrifying thought. More related content here.