I used some drywall tape and white gesso to get that grungy texture on the chipboard. Here's a quick tutorial on how I did it:
You'll need your layered banner pieces, some gesso, and some drywall tape. I stole the tape from my husband. That's the best way to get drywall tape, of course.
Cover the chipboard with drywall tape. I let the tape go over the edges and stick to the surface under the pieces. This helps them stay in place. Use a paintbrush to cover the chipboard in gesso.
Next, peel off the drywall tape. I peel it while the gesso is still a bit wet. I've found that it sometimes scrapes up the chipboard and is just hard to peel if you let the gesso get too dry.
After the gesso dries, I glue the top pieces onto patterned paper. Then I trim around the edges with my exacto knife. From there, it's just a matter of attaching the top banner piece to the bottom. I like to attach them so that they are slightly askew and the bottom piece shows through a bit.
Here's the end result:
UmWowStudio Products used: