drawing board [countable]
if you go back to the drawing board, you start again with a completely new plan or idea, after the one you tried before has failed:
The current system just isn't working - we need to go back to the drawing board and start afresh.
if a plan or product is on the drawing board, it is in the process of being planned or prepared:
Other car manufacturers have similar projects on the drawing board.
a large flat board that artists and designers work on