If you really want to make old-fashioned parchment, you first need to have a source of raw animal hides. Deer, goat and sheep hides are thin enough and strong enough for parchment. I don't know where you live, but deer hides are often available for free during hunting season. (If you know the right hunters!)

A good source of information is a tanning forum called The Hide Out! ( http://www.braintan.com/hideout/index.htm ) It's been a long time since I was there, but they had some good threads on making parchment.