Ad-hocing the Halftoning Process

I am interested in jury-rigging a basic halftoning setup to make screens for printing t-shirts from my negatives directly. I figured it would make a decent diversion. There are lots of different proprietary methods and different types of screens out there, or so this Agfa book I got from the library makes me think. Could anyone please point me in the right direction for resources on analogue halftoning?