I made sticks of explosive out of the hard cardboard tube that used to come on hangers for pants...about 12 or 14 inches long. Plug one end with wax. Fill it and tamp it really good with homemade gunpowder (thank you Encyclopedia Britannica). Top it with a model rocket engine fuse and seal that end with wax.

Pretty impressive explosion and a metric shit ton of smoke. Many a tree were laid waste thanks to the IEDs of my youth.