Create a folder in Dropbox (mine’s called “Printing”), and within that folder make two more folders: “todo” and “completed.” Then, fire up Automator. In 10.6, a box pops up asking you what type of template you want to use for your workflow. Choose “Folder Actions.”
At the top of the workflow, where it says “Folder Action receives files and folders added to…” choose the “todo” folder you created in your Dropbox. Then, in Automator’s search box, type “print” and you’ll see an item called “Print Finder Items.” Drag that into your workflow and select your printer (I left mine as default). Go back to Automator’s search box and type “move”. You’ll see an item called “Move Finder items.” Add it to your workflow and choose the “completed” folder you created at the beginning. Choose “Save as…” and give your workflow a name.
That’s it! Anything you drop in the “todo” folder (Ed. note: Which you can do from any phone or computer with Dropbox installed and connected to your home computer) will now automatically open its respective app, print it and file it for you.
If you’d prefer that your workflow just delete the files once they’ve printed, you can use the “Move Finder Items to Trash” in place of the “Move Finder Items” at the end of your workflow, too. Note that if you do this, you don’t need a “todo” and “completed” folder; you can just apply the folder action to your “Printing” folder.