I once saw in a video how someone created a set of paths which were alligend in perspective like this. Does anyone know how this can be done in best / quickest way?
Great question! Here's how I would do it. First start with the shape you want to duplicate. In your case it is a curve:
Draw a line with no stroke and no fill from your shape to the desired vanishing point and group them together.
Next use the Scale tool and place the Scale Anchor (the cyan cross-hair) at your vanishing point. While still in the scale tool, use alt and shift to duplicate the object to your first desired point.
After that just use Repeat Transformation (Command+D) to duplicate your object toward the vanishing-point!
