In the this picture, Master Craftsman Mike is installing the round window trim he custom made in his shop.
He cut such perfect circles, that the trim rolls smoothly across the floor. Pretty Impressive!
Mike cut the circle trim out using a template and a router. He then sanded the edges prior to installing the trim which is now ready for priming and painting. I actually found these windows online from another builder who was selling them as the project architect decided that they were not big enough for the house that they were going to be installed in.