Here is a amazingly accurate rule made by CNC laser cutting machines which makes it as perfect as you can get.
come see how it performs in my testing of this rule
also if your wanting one i have links to a big sale at Banggood.com for this tool at an amazing price

Drillpro 200/300/400mm Stainless Steel Precision Marking T Ruler https://bit.ly/35LONeZ
Summer Prime Sale 2021 https://bit.ly/3vE5qne
Banggood Summer Prime Sale 2021: Deals for Tools & Electronics https://bit.ly/2SGisTV