This prop was built out of a large cardboard tube, craft foam and balsa wood with an iPhone for a screen. The scroll wheel to the left of the screen is actually a rudimentary button over the iPhone's home button, allowing near full access to the phone's different functions. If my recording of Galaxy News Radio is interrupted by a phone call, I should be able to navigate to speakerphone and back without issue.
I started with carving a block of balsa wood into a basic shape with my Dremel, carving and gluing on details until It looked close to the way it looks in the game. The channel dial is a toothpaste cap, and the buttons/lights along the bottom of the screen were plastic bumps cut out of the bottom of medicine bottles. The arm band is a large cardboard tube with craft foam wrapped around it for shape. It does not open up, but I am able to slide my arm in easily with it still fitting snugly. A cardboard base with velcro connects the balsa wood face to the rest, and allows a way to insert my smartphone. The foam was sealed with Elmer's glue and the wood with a spray wood seal I found in the garage before I painted and weathered the whole thing with acrylics.
Walking around with The Ink Spots playing from my arm is incredibly satisfying, and when you bring your wrist up at the right angle, it actually feels like accessing a menu in game. Hopefully the neighbor's children won't complain too much when they get bottle caps for Halloween this year...
The below videos show how the whole thing looks with a proper screen on display. The first video demonstrates audio as well as use of the "scroll wheel" home button. The second video gives a view of the Pip Boy from various angles. On-screen images courtesy of Isaak at Console Alliance. He provides a couple of loopable videos of a Pip Boy screen for download here.
Here is a video demonstrating the unlock button, touchscreen navigation, and playing video and audio: