Make a Valentine and matching envelope using a page from your sketchbook. Above is a cropped photo of my layered valentine page. You'll see how I produced and printed cards and envelopes using a photo of this page.
As you'll see in this post, the layered journal page is made from a doodle on one page in my sketchbook and then covered with a sheet of vellum, with more ink drawings, filled with color pencil.
Envelopes: I photographed the ink doodle page, then, using Photoshop (filter: stamp) to simplify the drawings. Then I printed it out in black and white on regular printer paper, and then cut envelopes using the envelope template I found online.
Cards: To make the cards, I printed out the image in color on card stock. I made both postcards and folded cards, both to fit the envelopes.
|the vellum overlay. ink and color pencil|
Here' are the other pages of mine from my Strathmore Visual Journal (9x12). The doodles, painted with watercolor on one page, and the overlay of vellum, with more ink drawings (and colored with color pencil)
I used Strathmore Translucent Vellum and it took ink beautifully. ( I see they have inkjet and laser vellum too , but I haven't used it.) To fasten the vellum to the sketchbook page, I used a tiny hole punch and tiny brads. You could just staple it too.