I modified a wide-angle lens to allow it to take filter accessories such as a polarizing filter. I read a suggestion online somewhere. I first wrapped the barrel of the lens with gritty tape, then added a series of step-up and step-down adapters. These fit snugly outside the tape and allowed for a larger step-down ring at the front, to which I attached the actual filter. It was fairly inexpensive and allowed me to get the kinds of effects I like with my photos.