\version "2.19.47"

engrave =
#(define-void-function ()()
   (let*
    ; Create two layout definitions, independently from each other
    ((layoutOne
      #{
        \layout {
          \context {
            \Staff {
              \override TimeSignature.color = #blue
            }
          }
        }
      #})
     (layoutTwo
      #{
        \layout {
          \context {
            \Voice {
              \override NoteHead.color = #red
            }
          }
        }
      #})

     (layouts (list layoutOne layoutTwo)))

    (ly:book-process
     #{
       \book {
         \score {
           \new Staff { c' }
%           \layout {}
           address@hidden
         }

       }
     #}
     #{ \paper {} #}  ; non-functional, placeholder
     #{ \layout {} #} ; non-functional, placeholder
     (ly:parser-output-name))))

\engrave