Answer:
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?
A house of wood in a hidden place. Built without nails or glue. High above the earthen ground. It holds pale gems of blue.
What goes through a door but never goes in. And never comes out?
I am the tool, for inspiring many. Buy me in the store, for not much more than a penny. Don't overuse me, or my usefulness will go.
I build up castles. I tear down mountains. I make some men blind. I help others to see.
Break me and I am better immediately set and harder to be broken again.