Manifesto Board is a free composition board, you can use it as you please.
Contents can be related to all the 4 projects or even only one, it could also be a manifesto of your method, or an artistic representation of your design or whatever you would like to show.
Manifesto board will be rated as well and it also represents a good opportunity to impress the jury with those aspects that might not fit in the other boards or that better represent your ideas or details.