Since you're talking about plumbing - no, there's no reason why a plumber would want to use a clear piece of plexi on the end of a pipe. They'd just put a cap to seal off the end. I don't actually know, but my suspicion is that plexiglass would probably bond to PVC with PVC cement. That's easily tested with scrap. If so, get your PVC pipe and there are lots of fittings that will fit on the pipe and still be open ended - unions, adaptors. Go to Home Depot or Lowes and just shop. Assuming the glue works - glue on the fitting and then just glue on the plexi. You COULD just cut the end of the pipe, but using a fitting will give you a machined-flat surface to glue to.
It's the flash. Even when you are wearing make up, the flash of the camera can make your skin look WAAYYYY lighter. So before taking a picture, put on some bronzer. There are some lotions and also some powders that are bronzers. I have white skin and that happens to me, but by wearing bronzer my face doesn't look so pale.