This is what I do.
Go down to Wal Mart or wherever and get a 24" x 36" poster frame. Should cost about $10. Take out the paper insert that it comes with and turn it over. Using a yardstick, draw your 1" grid with a light pencil. Put the paper back into the poster from and there you go. Cheap, large, and durable. And if something happens to it, it only costs $10 to replace.
Go down to Wal Mart or wherever and get a 24" x 36" poster frame. Should cost about $10. Take out the paper insert that it comes with and turn it over. Using a yardstick, draw your 1" grid with a light pencil. Put the paper back into the poster from and there you go. Cheap, large, and durable. And if something happens to it, it only costs $10 to replace.