Flanger, I used to have rolls of beautiful lined GE drafting mylar, but to be honest, I haven't drafted by hand in more than 15 years nor have most people who do this for a living. It's all done on the computer. So this stuff isn't too easy to get locally.
But search the web for architectural supplies. http://www.artsuppliesonline.c...og.cfm?cata_id=13655