+ else
+ # manually drawing the 3x4 boundaries ...
+ draw_cyl $x0 $y0 $z0 $x1 $y0 $z0
+ draw_cyl $x0 $y0 $z0 $x0 $y1 $z0
+ draw_cyl $x1 $y1 $z0 $x1 $y0 $z0
+ draw_cyl $x0 $y1 $z0 $x1 $y1 $z0
+
+ draw_cyl $x0 $y0 $z1 $x1 $y0 $z1
+ draw_cyl $x0 $y0 $z1 $x0 $y1 $z1
+ draw_cyl $x1 $y1 $z1 $x1 $y0 $z1
+ draw_cyl $x0 $y1 $z1 $x1 $y1 $z1
+
+ draw_cyl $x0 $y0 $z1 $x0 $y0 $z0
+ draw_cyl $x0 $y1 $z1 $x0 $y1 $z0
+ draw_cyl $x1 $y0 $z1 $x1 $y0 $z0
+ draw_cyl $x1 $y1 $z1 $x1 $y1 $z0