Moving away from the plywood idea and back to the question of paper-

A good art supply store- a real one, not a craft store like Michael's or something like that- should have rolls of graph paper 36" wide or wider you can purchase by the yard or foot. Usually they're lined in fractions of an inch, like 1/8, 1/4, or whatever, or 1/10s of an inch. I've also seen metric in catalogs, but not at the stores I've shopped at.

Now- thanks to my wife, I also know that many fabric stores and nearly all quilt shops carry graph paper up to 24x36 for quilt layout. The stuff my wife has is gridded in 1/4" squares.

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