Step 4: Crimping
This step is key. If the crimp is not tight enough or is not correctly done, the rocket will just burn. It may be a bit complicated but after you do one and see what I'm talking about, it should come easier. Start off by inserting your crimping spacer, feeding the fuse through the hole, until the masking tape stops it from entering any further. Next feel around for the space that is created between your spacer and the bottom of your fuses and work it around and squeeze it. You want to make it weaker than the rest of the tube so it will fold easily. Now firmly grip the top of the rocket with one hand and the spacer with the other. Slowly twist and push until the paper folds down nicely. To finish it off, tie a knot around it with your string to keep it from unfolding.