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Have a look at the video for more details and true slow motion examples.
First you will need KNO3 and caster sugar, mix them together well with a 65 to 35 ratio. Then ad just enough water until it is diluted and stir well. Put it on a low heat and constantly stir, after about 15-20 minutes it should start to crystallise and then turn into a dough like texture. Roll it into small balls or pellets and let it dry.
Just simply use a pvc pipe, duct tape a cone shaped wod on the end (don't be afraid to use a lot of tape)
Fill the rocket with KNO3 and slightly compress it.
For the combustion chamber use a piece of wood rod that is slightly bigger than the pvc drill a whole in the wood then knock the wood into the pvc with a hammer and super glue it, Now your finished! Good luck with launching. if you have any question that I haven't covered feel free the ask me.