https://hackaday.com/2026/01/24/ancient-egyptian-flatness/
Making a truly flat surface is a modern engineering feat, and not a small one. Even making something straight without reference tools that are already straight...
ancient egyptianflatnesshackaday
https://www.nist.gov/publications/interferometric-testing-photomask-blank-flatness
Conventional interferometric testing of the flatness of photomask blanks is rendered difficult by the long coherence length of the HeNe laser sources typically
interferometrictestingphotomaskblankflatness
https://www.graffitistreet.com/store/add-fuel-az367-flatness-tile-2021/
Nov 22, 2025 - Medium: Gel and Ink on ceramic tile, PVC mount. Edition: 50 Size: 20 × 20 cm Description: Signed and numbered by The Artist. Year: 2021
add fuelflatness