I would like to create a rectangle from two given 3D points (they are placed on rectangle diagonal). Those points lies on the same plane with given normal. I was able to do it on axis aligned planes, but now I would like to do it on any plane.
Any ideas if this is possible and how?
If $A,C$ are your two points, let $S$ be the sphere with $AC$ as diameter. Let $O$ be its center. Then pick any $B\in S$ and let $D$ be the other point of intersection of the line $BO$ and $S$. Then $ABCD$ is a rectangle. If you have an additional restriction in form of a plane through $A,C$, then the sphere becomes a circle (by intersection), but that still leaves you with a one-parameter faimily (as hinted by user86418).