Some kids built homemade stuff starting in the 8th grade, but somehow, that was different. It
was a science experiment of sorts. The chemicals that an 8th grader could get in the early 70's at the hobby shop, not to mention the bags of saltpeter in the grocery store made childhood interesting. Brisance was a blast baby.
IIRC, someone found some SF "cookbooks" on the subject hidden down in the creek.
More fun than the occasional skin mags that were floating around down there.
Of course, I just heard about this stuff second hand.