Código:
public class Geneuno extends javax.swing.JFrame {
DefaultTableModel Tabla1 = new DefaultTableModel();
Icon Acero = new ImageIcon(getClass().getResource("../Ima/Acero.gif"));
private void CbSelMetActionPerformed(java.awt.event.ActionEvent evt) {
if (CbSelMet.getSelectedItem().equals("Metal")){
Tabla1.addRow(new Object []{"",new JLabel(Acero),"",new JLabel(Acero)});
}
}