Export image from clipboard to folder

I create a lot of mockups for my mobile phone. I recently heard of the brilliant idea to just put your current mockup as an image into your Dropbox (or whatever cloud your using). Then just take your phone and open the image. This is a lightning fast way to check how your layout feels in your hand and how reachable everything is. Also your colleagues can check it out and keep track of what you're doing / give you feedback.

I'm working with Balsamiq Mockups. I would like to: 1. Mark some items on the screen 2. Precc Command+C 3. Press

And now there should be an image in a specific Dropbox folder with the marked items. Currently I paste the clipboard to Photoshop and then export it, but I would like to find a way to further automate this.

I'm not that familiar with OSX.. Can I write a script for this? Would the Automator help?

EDIT: In the meantime I found out that there are apps that let you open Balsamiqs .bmml files and thus actually letting you interact with them ('clicking this button brings you to this screen') on your phone. I didn't try it yet, but thought it might be of interest to people stumbling on this question.