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I built one in the late 70's
started off slow then - whoosh - like the big boys.
My dad would send me off to buy fertilizer for the family orchards as soon as I was legal to drive. Urea and other harmless stuff mostly.
And then I'd forget, oh yeah, potassium or ammonium nitrate too. Skip the the family farm purchase orders, I've got cash.
The boss fertilizer guy maybe knew what I was about, but he didn't give a shit. Cash is cash.
I built quite a few sugar rockets, many the dangerous PVC pipe sort. Making sugar rocket fuel in the backyard.
My first and last experiment with ANFO big high explosives was successful. I'm fortunate only to have lost a bit of my hearing and not to have been hit by any big rocks falling out of the sky. Many big rocks were falling out of the sky and there was a crater. I didn't know shit immediately, and it's never going to be more than concussion 
lost and recreated memory. But the crater was there for a few years.
Earlier experiments had only left me with shrapnel in my back, and my younger brother had explained to my mom the holes in my jacket and wounds as falling into the prickly pears. He kindly removed the bloody shrapnel and did not confess.
It was an honest deal, I was keeping some of his secrets too.