Any way to export dimensions of UI elements?

On our current project, we have someone who is going to be doing UI artwork for us and they need to know the current placement of all the various UI elements in the game. For example: We need to know that our shop window is 300x300 units, each item icon inside it is 35x35 and the locations of them relative to the shop window, etc etc

Is there a plugin or script that can export the various dimensions or sizes of various UI elements relative to each other?

Thanks
-Dave