Rainy day here in New England.  Good day to play with gelatin printmaking.  I have worked out a good system for cropping down the prints to the artist trading card size. 
  1. Start with a small print- 3″ by 4″
  2. Use a Matt with a 2.5″x3.5″ window to select the best composition
  3. Poke the corners of the cropped image with a pin
  4. Flip the print over and apply glue to the area between the holes
  5. Using the pinholes as a guide adhere a sturdy card to the back
  6. Trim the print down to 2.5″x3.5″
  7. Put your label and information on the back