Here's Loren Miller, apparently; at least he worked at the Wharton School at the right times. https://www.linkedin.com/pub/loren-miller/6/4a7/2a8
If you get the archives, let us know. I want a copy. This is a serious blast from my past I had forgotten about!
Not sure what size you're looking for, but here are a couple:
https://www.amazon.ca/Koala-Tools-Geometric-Transparency-Variety/dp/B07D32F5GY/
https://www.amazon.ca/CZYY-Acrylic-Square-Overlay-Durable/dp/B07T3L2G5V/