So, I’ve found this interesting article on SparkFun discussing the fate of a particular IMU (Inertial Measurement Unit) that has been discontinued by its manufacturer, and reflects on the larger issue of parts being discontinued and their effects on higher-level projects.
“Another One Bites the Dust”
20190108/https://www.sparkfun.com/news/2851
F.Y.I. “Rubylith” integrated circuit design masks are the kind where a mask is cut away by hand.
20190108/https://en.wikipedia.org/wiki/Rubylith