drawing board
noun /ˈdrɔːɪŋ bɔːd/
  /ˈdrɔːɪŋ bɔːrd/
Idioms - a large flat board used for holding a piece of paper while a drawing or plan is being made
- an architect’s drawing board
 
 
Idioms 
(go) back to the drawing board 
- to start thinking about a new way of doing something after a previous plan or idea has failed
- They rejected our proposal, so it’s back to the drawing board.
 
 
on the drawing board 
- being prepared or considered
- It's just one of several projects on the drawing board.