Ok I cheat a little on this, if you google vintage maps and books you can save the images to print out later. I shrink and colourise the image, print it out on paper or card then if it's white I age it with some cold tea, then burn the edges with a match.
Love it- the books are great, and I think the hat is awesome- I just finished reading one of Terry Pratchett's Discworld books to my wife- the hat made me think of the hats described for the 3 witches...