(In the bottom-right corner, you can see the tops of some of the exciting Workplace Awards I've won. Inexplicably, our award certificates all say: perseverence is very important to success. how else would two snails have made it to the ark?)
Office Supplies needed:
UPS/Fedex legal-sized window envelopes (unused, unless they're in really good shape)
Legal-size plain paper
To make your own prints, you'll need some kind of image-editing software that lets you set the page size (I used MS Publisher). Otherwise, you can download a pdf version of the vintage office close-ups I used here! (I got the images from google image search so at least a few of them are probably do-not-use-for-commercial-purposes, so don't sell your envelope art to your coworkers for lunch money.)
Cut off the top "flap" of the envelope that would normally be used to seal it. Because my cubicle has panels with horizontal gaps, I just folded the flap backwards and stuck it in the gaps, but usually you would cut it off. Use tape or tacks to stick your envelopes to your cubicle wall.
Design & print your images onto legal-size paper (note: I'm sure all of this could be done with letter-sized envelopes and paper, but I chose legal size so the envelopes have a bigger pocket). If you're designing your own art, you'll want to create an image that's 13" x 7", including any border you're using. Once you've printed the images, cut the image out so you're left with a 13x7 page.
Slip images into the envelope "window" and admire your handiwork! Swap the images out whenever you get bored with your decor. Use the envelopes to sort your working documents, mail, or just as decoration.