drawing board

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A large flat board on which paper or canvas can be spread for drawing.
• idiom (back to the drawing board) Back to the beginning or the planning stage after an approach has proved unsuccessful.
• idiom (on the drawing board) In the planning stage; under consideration.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A plane wooden construction or table to which paper can be fastened for drawing purposes.
• noun figuratively Used to refer to the planning stage of a project as in:

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a smooth board on which paper is placed for making drawings