Home made napalm:
Take any amount of gasoline, or diesel, and add styrofoam to it. As you know, this will desolve. Add it until it won't dissolve anymore, or until it's as thick or as thin as you'd like. This gooey goop is extremly flamable and burns for quite a while, and since it sticks to the skin it's nearly impossible for someone in shock, or panicking to wipe off.
P.S. Stop, Drop, and Roll, does not work with this sh*t, it just spreads it around, and affects a bigger area
I invision loading a cannon (cement mixer, or any long tube) with gun powder, and pack it down, then pour this down the tube and fire before the gunpowder gets too soaked. The explosion would light the "napalm" and send a shower of lava on anyone down range, while the "enemy" is running around screamming "mommy" like a chicken with it's head cut off, you proceed to take they're government supplied arms.
I also know how to make a zip-gun out of any clicker-type (no lid, tip goes in and out) ball point pen, a tack, or screw, or nail, and a .22 shell. Very simple, but metel sided pens are recomended for those who enjoy the luxury of fingers
However, I wouldn't recommend leading an army with this type of weapon. a bow & arrow would be better than this, but the bottom line is, Two out of three house-hold products are flamable these days, and anyone who can put a dent in the back side of a bullet can make a gun.