I am making parts about 3mm thick and 40 mm long (sections of window frame for model boat) and within a day of printing they tend to curve. I've tried two different surfaces to contact the plate. So is this due to differential shrinkage? Strength is not too important for this part so I could minimise post-curing. Also, is there a benefit of using longer exposure times during the printing so it is more cured already? The photo shows a whole frame, but in fact I cut it into 4 sections in the CAD drawing, and print them horizontally. I'm also thinking to use clear resin so perhaps the post-curing light would penetrate more evenly.

frame and section.jpg