Is it possible to apply a drop shadow effect to an object and then somehow make the object itself invisible while the drop shadow remains visible?
Answer
If I’m understanding your question correctly, then the effect that you are looking for can be achieved by creating a white object with a drop shadow and then setting the whole thing to MULTIPLY / DARKEN / OVERPRINT.
The result would look something like this:
Attribution
Source : Link , Question Author : JoSch , Answer Author : Westside