1. The Bleach Bomb
What's in bleach? Sodium hypochlorite. What's in drain cleaner? Hydrochloric acid. When you mix bleach and an acid-containing drain cleaner, a spontaneous chemical reaction occurs: NaClO + 2 HCl ? Cl2 + H2O + NaCl
The reaction produces poisonous chlorine gas and likely leaves unreacted hydrochloric acid as well. Chlorine gas, even small amounts of it, is bad stuff. As WWI graphically demonstrated, it attacks the membranes in your eyes, throat, and nose, and prolonged exposure can cause death by asphyxiation.
2. Thermite
Not many chemical processes are as gloriously, vigorously, and robustly exothermic as the thermite reaction. Take powdered aluminum (say from the inside of an Etch-a-Sketch) and rusted iron (say from a well-weathered steel wool pad) in just the right proportions and ignite with a sparkler. The reaction that ensues is hot enough to burn through dirt.
3. Styrofoam Napalm
Vietnam War-era napalm was made by mixing of benzene, gasoline, and polystyrene. The stuff was a hellish mixture that clung to surfaces while it burned, and it was practically inextinguishable. It's possible to come up with something pretty darn close to the vintage napalm by simply dunking Styrofoam in a bucket of gasoline, mixing it around for a while and reserving the leftover goo.
4. Maglite Laser
Myriad YouTube videos show how to make a retina-melting, flesh-burning portable laser from a discarded DVD burner and Maglite flashlight. If you remove the laser diode from the burner, then swap it out for the bulb of the Maglite, you essentially turn the flashlight into a handheld, intensely concentrated laser.
source : http://gizmodo.com/5939234/7-deadly-weapons-you-should-never-ever-make-out-of-harmless-household-items
