There's something about imperfections that makes a photo really interesting. Imperfections in a photo such as obscuring a part of the lens, lens flares, or light rays can make a photo more visually interesting. They could change the mood of a photo, making the scene more angelic, or even retro through the use of lens flaring or rainbow effect. One way to introduce these photo imperfections is through the use of a glass prism. The glass prism can have several effects, depending on how you're holding it to the lens. You can use it to split white light into a rainbow of colours. The prism, can be used as a sort of mirror to reflect other parts of the scene into the frame. Finally, it can be used like any sort of glass - to obscure the lens and add a nice soft blur.
Below are some examples of ways I've used a glass prism in my photography.
Don't just stop at glass prisms, you can take it further by obscuring the lens with other items. Whether it be a piece of acrylic, metal, cloth, or even your finger - there are so many different effects you can create. Experiment yourself and find out what technique or material compliments your style of photography best.