On a floured surface, start by rolling out a fist-sized ball of pie dough into a long, thin rectangle or oval. Using a knife, cut it into strips about ½ an inch thick. Loosely braid them together, and then cut off any excess dough at the end of the braids. Repeat as needed until you have enough braids to cover the circumference of the pie, overlapping and cutting off the ends if necessary. If your braid doesn't stick easily, try brushing the edges with a little water or egg wash to act as a glue.