Printing in Trello
We built Trello to be a next-generation web and mobile application, so as such it doesn't have great built-in printing support. You can try printing individual cards and boards, but results may be mixed.
To print all of the cards on a board open the board's menu, then click "More" and select "Print and Export". You will then want to select "Print" from the menu
Print the cards on a board from the board's menu.
To print an individual card open the card that you would like to print and under "Actions" on the right side of the card select "Share and more...". You will then want to select "Print" from the menu.
This article provides a good workaround for using a Google extension to help with Trello printing: http://webapps.stackexchange.com/questions/19631/how-do-i-print-a-list-in-trello-for-offline-use