Way back in the day after Piece of mind came out I actually made my first shirt. It was eddie's head from Number of the Beast. Back then we had to hand cut the pattern on ruby lith and then fix it to the screen and hope to hell it worked. It worked well. I'll have to find it and scan it.
When I did this we were learning "Basic" in computer class. There was no files back then. Only a handful of people had computers. Mostly vic20 or Commadore64. The stencil for this was hand cut and applied to the silk screen.