The rectangle is fairly simple, just make 2 variables: a start corner, and an end corner for your rectangle. When the player presses the mouse button, set the 1st variable to be the ‘Project World Location to Widget Position’ (the World Location input should be the location from (Get Player Controller -> Get Hit Result Under Cursor by Channel)) return value, which will be a 2D Vector (x & y), now do the same thing for the 2nd variable when they release the mouse. You now have two variables representing the top left and bottom right corners of your rectangle. As far as the showing it while it is dragging, instead of setting the 2nd variable when they release the mouse, set it every frame until they release it.