Here's an example of how she made two different cards with mirror images:

 

Or, perhaps even more fun, put the mirror image and original image on the same card!...

Here's how it's done:

• Ink the stamp to be mirrored. 
• Press the stamp against the MirrorIt! Pad.
• Press the MirrorIt! pad against the paper (or whatever else you may be stamping on!)
• Presto! You have the image you always wanted reversed!
• Clean the pad after each use.

These Mirror It! stamps are available in 3 sizes - Small, Medium & Large