Panelizing a PCB is simple, at least as far as the artwork goes. I've tried panelizing a finished design using both Cadence and Altium, but I couldn't figure out how to panelize drill files in either piece of software. I wrote two simple Python scripts that automate the task. After panelizing the artwork, these scripts can take care of the drill files for you. panelize.py combines NC drill files from different designs into a single file, where each drill coordinate is offset by a specified amount. panelize_array.py works with a single input drill file and returns an arrayed version of it. If you want to use these files there is more information when you read the headings in the source code that describes input formats and proper usage.