Jameco’s “Easy PIR Alarm Kit” is a neat little kit that would make a great introduction to dead bug electronics assembly and the basics of PIR detectors, transistor switching and relays.
Source: JE-PIR ALARM: Jameco Kitpro : Easy PIR Alarm Kit : Electronic Kits & Projects
I’ve been doing dead bug assembly for custom one off circuits for over forty years and there’s no doubt it can be the perfect solution for some circuits.