Answer:
I can be as thin as a picture frame but my insides have many things you can see.
Low on cash? Pick out items from this rack.
You might accuse someone living with a stolen identity of being this.
What instrument can you hear but never see?
Very helpful if you intend to go gently down a river.
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?