C#

// Declared in class to cache PaperSize;
private PaperSize paperSize;
 
// Method to enumerate PaperSizes from selected Printer.
private PaperSize GetPaperSize(PrinterSettings printer, PaperKind kind)
{
  if (printer == null) throw new ArgumentNullException("printer");
  if (this.paperSize == null)
  {
    foreach (PaperSize size in printer.PaperSizes
    {
      if (size.Kind == kind)
      {
        this.paperSize = size;
        return this.paperSize;
      }
    }
  }
  else return this.paperSize;

  // Only occurs if requested PaperSize with PaperKind doesn't exist.
  throw new ArgumentException("The requested paper size is not supported " +
    "by this printer.", "kind");
}
 
// Handler for PrintDocument.QueryPageSettings event.
private void printDocument_QueryPageSettings(object sender,
  QueryPageSettingsEventHandler e)
{
  try
  {
    e.PageSettings.PaperSize =
      this.GetPaperSize(e.PageSettings.PrinterSettings, PaperKind.A3);
  }
  catch (Exception ex)
  {
    MessageBox.Show(string.Format("Could not print the document: {0}",
      ex.Message), "Print Error", MessageBoxButtons.OK,
      MessageBoxIcon.Error);
    e.Cancel = true;
  }
}