I had a stenciling class here in the Studio recently and shared a quick way to prep card bases with a gorgeous stained glass cross for your Easter or sympathy cards this year!
Apparently I never took a photo of the finished project, though... so you'll have to fill in the details using your imagination! Sorry about that! 
Cut a card base of 4 x 5.25 inches (one step down from your card base size.) Use four Post-it Notes to mask off a cross shape. Here's an easy way to line them up!
These are standard sized notes that are 3 x 3 inches square. Think of each note as being a grid of four identical squares. The top two notes cover the two cardstock upper corners with just one square of that "grid." The bottom two notes cover the cardstock's lower corners with two squares of that grid. Make sense?
When you have your cross masked off, take a pen or pencil and mark it as shown. You might also want to label which corners are which. You can stack the reusable post it notes and keep them with your stencils as an easy reminder of how to do it next time!

Position your stencil (from the Plenty of Patterns pack) over the cross shape until arranged as desired. I wanted the maximum number of "joins" where the lines intersected, so that's why mine is slanted at an angle. Tape down at top and bottom so you don't have to try to hold it in place while we sponge.
Start with your lightest of three coordinating colors for the stained glass. I used So Saffron, Calypso Coral and Gorgeous Grape, warm springy Easter tones, but you can use any three shades you prefer.
I used Blending Brushes for this technique, but you can also use sponges or daubers if you prefer them.
Lay down a basic coat of the lightest color ink first, then the medium, concentrating on leaving space for the yellow to show through.

With your final and darkest color, add it in just a couple of strategic locations, so the two previous shades shine through.

TIP: if you have a little trouble with some blotchy color that won't blend, add a drop of glycerin to your sponge and pat it on. In a moment it will re-moisturize and allow the ink to spread more easily. Be aware that ink blended with glycerin will take longer to dry than ink alone.

Then comes the fun part! Peel off the stencil and post it notes and you have a clean, sharp cross design on your background. If you'd like a softer look, buff around the cross with the same pale color as your first ink.
Finish the card with a banner or drape across the horizontal bar, or a sentiment stamped in the lower right corner.
Thanks for coming to Song of My Heart to find inspiration today! I appreciate your visit. Feel free to reach out if you do not have a Stampin' Up demonstrator meeting your creative needs, and I'd be happy to welcome you in. Happy Stampin'!