Ask scientists of a certain age about their childhood memories, and odds are they’ll start yarning about the stink bombs and gunpowder they concocted with their chemistry sets. Dangerous? Yes, but fun.

‘’Admittedly, I have blown some things up in my time,’’ said William L. Whittaker, 64, a robotics professor at Carnegie Mellon University who unearthed his first chemistry set, an A.C. Gilbert, in a junkyard around age 8. By 16, he was dabbling in advanced explosives. ‘‘There’s no question that I burned some skin off my face,’’ he recalled.