It's made from a type of kraft paper and for the life of me I can't recall its name. Anyway hard to find as I tried with no success.
Most people just use coloured paper.
The ones I did were the fawn colour so I test printed on white paper to get my spacing and used masking tape over the top and reprinted.
Came out very well with the texture from the tape on it.
Wrappers are here....
http://www.pinballrebel.com/pinball/
