Magnet sheeting may be made of PVC and cutting it in this manner may produce small amounts of extremely toxic chlorine gas. I am not sure. You do this at your own risk.
Step 1: Go make your word file.
Open Corel Draw and make a text block the size of your scrap magnetic sheeting. My scrap sheeting was 3.5" x 24" and as such I wrote enough semi-random words to fill that space.
The text should be of transparent fill with a 1 pixel black outline.
For a better example download the attached work-file below.