For those interested, there is a nice article in the current issue of
Home Shop Machinist (March/April 2005, page 30) by Steve Archer about how to build a simple folder using a CNC mill and custom jigs. Even if you don't have CNC capability, but you have a mill, the jigs, fixtures and setups are interesting and illustrative, especially for beginners.
Unfortunately, the article is not available online, but you can subscribe to
Home Shop Machinist here , or you can pick up a copy at a well-stocked news stand or bookstore, or at your local library. (I am not associated with the magazine in any way other than as a subscriber, so this is not spam.)
I have also posted this message in the General Discussion forum for wider dissemination.
-Frank