Have you seen the price of precision metrology equipment lately? Neither have I, I've been too busy rubbing these sticks together in an attempt to find flatness.
Patreon: https://www.patreon.com/NotAnEngineer
Here's Alex's channel: https://www.youtube.com/@anengineersfindings
And some better reference material on the three plate method, if you're interested:
Accidental Science:
Flat From Scratch, revised - The 3 plates method
Robrenz:
ROBRENZ ATD #1 INTRO, 3 PLATE METHOD
Oxtoolco:
Making flat lapping plates 1