I am looking for a way to print on apps created by Air. On smartphone devices, I had send a mail containig the data I want to print, and on desktop apps, I saved a text file, which the user can then print. Is there a better way, which is not too complicated?
For desktop I would suggest you to use the PrintJob class (https://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/flash/printing/PrintJob.html) - its pretty straight forward and easy to use.
You may need to play around a bit with the scaling of the items you want to add to have it fit well onto the page.