Hand made cards are a nice gift idea, especially on Valentine's Day. Here is a cute design that you can print out, slice with a razor blade or x-acto knife, and fold into a pop-up "I Love You" card. photo: martha stewart CLICK AND PRINT THE GUIDE BELOW: You'll Need: This free printable A solid color paper of your choice to layer Sharp x-acto knife or razor blade Directions: Carefully slice where the solid lines are (remember to cut out the center of the heart) Fold the card in half Open the…