"Inadvisable experiments with Estes motors" was a staple of the 2000's for me.
Unfortunately around 2009 or so there was a change in regulations that made them practically unobtainium in my home country, the importer started getting demands from customs for an "explosives permit".
Let's talk about Estes model rocket D-size engine bazookas. Because that's where the 70's really shined.