Magic ~~~ the Trellis (or Lattice) Card.
Watch on YouTube: HERE
One option that I would use, would be to glue the patterned paper to the inside front of the card, just on top of the trellis window (facing patterned side of the paper toward the front, of course, so it shows through the trellis). I would do that so that I could still put a sentiment or writing inside the card without that showing through to the front. I would also decorate that right-side sentiment inside as well, and have the sentiment on top of matching patterned paper. Does that make sense?