First off, homemade napalm is in no way illegal, nor does it explode. You've watched too many Vietnam movies. What it does do is burn. Forever. More on campfires to come.

Put a couple of fingers of unleaded in a pickle (wide mouthed) jar, stuff waste Styrofoam in it. You can jam the contents of a 40" TV packaging in a quart jar.

That's it, that easy. Keep cramming the foam in until you get a taffy consistency. Too much and it's too hard to dig out with a stick. Too little and it slips off your stick.

I keep a jar at my campsite and one in the house for starting our little fire pit. A golf ball chunk will start soaking wet kindling.

PRO TIP: Spread the goo on a cookie pan, 1.4" thick, let it dry in the summer sun, cut into little pieces with scissors, put it in a little plastic box (that you had saved already, right?). Now you can pack it out with no mess, no smell!

Never goes bad, as far as I know, can't be too dry.