multiple dynamic file storage for paperclip

attachment.rb

module Paperclip
  class Attachment
    attr_accessor :queued_for_write, :queued_for_delete
  end
end

gistfile1.rb

@attachment.instance.extra_files ||= []
@attachment.instance.extra_files << File.join(File.dirname(@attachment.path), "special_output_file_name")

gistfile2.rb

    def queue_existing_for_delete
      return unless file?
      @queued_for_delete = [@queued_for_delete, instance.extra_files].flatten.compact.uniq
    end

gistfile3.rb

serialize :extra_files

interpolations.rb

module Paperclip
  class Interpolations
    alias :old_extension, :extension
    def extension(attachment, style_name)
      if it_is_one_of_the_special_files # this test depends on the situation
        ext = File.extname(style_name) # rip off the extension
        ext.slice! 0
        ext
      else
        old_extension
      end
    end

    alias :old_style, :style
    def style(attachment, style_name)
      if it_is_one_of_the_special_files
        File.basename(style_name, File.extname(style_name))
      else
        old_style
      end
    end
  end
end

processor.rb

module Paperclip
  class MyProcessor < Processor
    def make
      Paperclip.run "yourfancyprocessor", "args"
      @attachment.queued_for_write["special_output_file_name"] = File.open(File.join(File.dirname(@file.path), "special_output_file_name")) 
    end
  end
end