She had a paper punch that was 2" x 2". So I designed her a stamp that would fit on her punches (In Adobe Indesign but you could use Photoshop or Illustrator as long as it is saved as jpg). I made sure the file size was 2x2" 300 res. Background was 100% white, text and graphics were 100% black. Saved as JPG and uploaded the image to www.rubberstamps.net art-mounted stamps. For less than $18 (that's with shipping) she now can make as many business cards on whatever media she wants.
Here is a photo of the stamp
She had these little plastic holders which work perfectly.