I have been experimenting with applying style sheets to the label data to improve the formatting of the labels. By applying a class to each of the fields I was able to change font, colour etc but the feature I really wanted, positioning, does not work. It seems this is not implemented in tcpdf. Because of this I wonder if a different backend should be considered such as dompdf. This uses tcpdf to do the backend work but does fully support css. If we changed to dompdf the label positioning would have to be done by css as well which should not be too hard??
So of these ideas come from an email I received from another user who wanted to achieve what is shown here http://drupal.org/node/1345182
Something to think about.