If you had to print a flat panel, say 3 x 25 x 120, what material would you use for the flattest result? I know orientation would be important, my head says make sure the longest edge is perpendicular to the build plate.
I’m sure the Rigid would give the most accurate results, but it can be a bit brittle, feels lovely though! I wondered if the standard primaries would be similar, or the tough. I think the Durable would flex and distort too much.
Tough and Durable would flex too much, however you could print it with Tough and post-cure it with weights or ties on it to keep it flat. Main issue is it tends to creep when under constant load.
Rigid is way less brittle than the standard resins from my experience and is my go-to resin choice for thin parts. but Grey Pro will work similarly with a 3mm thickness.