Lee Filters are hand made and according to one of our members they are the Rolls Royce of filters (and cost accordingly). In the words of Lee Filters:
Our reputation has been built on the fact that every filter that leaves the factory has been individually handmade and inspected by one of our technicians, who ensure it meets our exacting standards.
Anything that will compromise picture quality is simply not an option.
The following link will take you to a video of how these filters are made:
http://www.youtube.com/watch?v=lMu_m203YaY
Thanks to Adrian T for the link.
