Precision measurements
I love precision measurement instruments, and Mitutoyo makes some of the best.
Since I'll likely never drive a Porsche or own a Leica, I like to think of this as enjoying that ๐ workmanship on a budget.
Today in the mail I received two Mitutoyo gauge blocks (one pictured below). I'll be using these to demonstrate the phenomenon of wringing gauge blockstogether. I have no other reason to own gauge blocks, which are typically used in high precision manufacturing situations.
As you might guess, the first thing I did was measure in my micrometer. Seeing as the Micrometer was "new old stock" when I bought it and I have no idea of its age, it was extremely satisfying to see everything measure up, literally, as expected.

The gauge block also came with a 2013 letter of certification letting me know that its nominal length was inspected as accurate to within 1.2ยต Inches.