Printing LilyPond PaperColumn and NonMusicalPaperColumn

Both PaperColumn and NonMusicalPaperColumn can take a stencil.

   \paper { ragged-right = ##t }
   \layout { \context { \Score
      proportionalNotationDuration = #(ly:make-moment 1 64) } }

   \new Staff {
      \override Score.NonMusicalPaperColumn #'stencil = #ly:paper-column::print
      \override Beam #'positions = #'(-4 . -4)
      c''8 [ e''8 g''8 b''8 ]
   }

   \new Staff {
      \override Score.PaperColumn #'stencil = #ly:paper-column::print
      \override Beam #'positions = #'(-4 . -4)
      c''8 [ e''8 g''8 b''8 ]
   }

The key here is that both PaperColum and NonMusicalPaperColumn subscribe to the paper-column interface.