diff --git a/battery-case-generator.py b/battery-case-generator.py
index 322360e..4e0a1ae 100755
--- a/battery-case-generator.py
+++ b/battery-case-generator.py
@@ -18,7 +18,7 @@ parser.add_argument('--padding', default=1.5, type=float, help='Padding around h
 parser.add_argument('--outside-padding', default=4, type=float, help='Extra padding between holes and wall')
 parser.add_argument('--thickness', default=3.0, type=float, help='Thickness of material')
 parser.add_argument('--lid', default=0.2, type=float, help='How much extra play to give the lid')
-
+parser.add_argument('--verbose', action='store_true', help='Print computed parameter values')
 args = parser.parse_args()
 assert (args.dimension % 2) == 1
 
@@ -46,16 +46,18 @@ args.corner_s      = args.corner*args.stretch
 args.corner_radius = 3*args.corner_s/math.pi
 args.corner_inset  = args.corner_s*math.sqrt(3)/math.pi
 args.interior_edge = args.grid*args.dimension*0.5+args.outside_padding
-args.exterior_edge = args.interior_edge+args.thickness
+args.exterior_edge = args.interior_edge+2.0*args.thickness
 args.interior_leg  = (args.interior_edge-args.horizontal_finger-args.kerf)/2-args.corner_inset
-args.n_hor_fingers = int(args.exterior_edge/args.horizontal_finger/2)
-args.exterior_leg  = (args.exterior_edge-(2*args.n_hor_fingers-1)*args.horizontal_finger+args.kerf)/2
+finger_length      = args.interior_edge-2.0*args.corner_inset
+args.n_hor_fingers = int(finger_length/args.horizontal_finger/2)
+args.exterior_leg  = (finger_length-(2*args.n_hor_fingers-1)*args.horizontal_finger+args.kerf)/2
 args.exterior_slot = (args.exterior_edge-args.horizontal_finger+args.kerf)/2
 args.n_ver_fingers = int(args.height/args.vertical_finger/2)
 args.vertical_finger = args.height/args.n_ver_fingers/2
 args.slots         = [args.vertical_finger*2.5-args.thickness*0.5, args.vertical_finger*4.5-args.thickness*0.5]
 
-print(args, file=sys.stderr)
+if args.verbose:
+    print(args, file=sys.stderr)
 
 DIMX   = 5.0*args.grid*args.dimension
 DIMY   = 3.0*args.grid*args.dimension
@@ -74,7 +76,7 @@ def draw_grid(cx, cy):
             HOLES += '<circle cx="%.2f" cy="%.2f" r="%.2f"/>\n' % (cxr+col*args.grid, cyr, args.radius)
 
 def draw_plane(cx, cy, interior=False):
-    global SHAPES
+    global HOLES, SHAPES
     if interior:
         edge = args.interior_edge
     else:
@@ -96,25 +98,60 @@ def draw_plane(cx, cy, interior=False):
             turtle.forward(args.thickness)
             turtle.left(90)
             turtle.forward(args.interior_leg)
-            turtle.circle(-args.corner_radius, 60, 5)
+            turtle.circle(-args.corner_radius, 60)
         turtle.forward(args.interior_edge-2.0*args.corner_inset)
-        turtle.circle(-args.corner_radius, 60, 5)
+        turtle.circle(-args.corner_radius, 60)
     else:
         turtle.pendown()
+        for side in range(6):
+            turtle.forward(args.exterior_edge)
+            turtle.right(60)
+    SHAPES += '<path d="%s"/>\n' % turtle.to_s()
+    if not interior:
+        turtle.reset()
+        turtle.penup()
+        turtle.forward(args.interior_edge)
+        turtle.right(120)
+        turtle.forward(args.corner_inset)
         for side in range(5):
             for finger in range(args.n_hor_fingers):
                 turtle.forward(args.exterior_leg if finger == 0 else args.horizontal_finger+args.kerf)
-                turtle.right(90)
-                turtle.forward(args.thickness)
+                turtle.pendown()
                 turtle.left(90)
+                turtle.forward(args.thickness)
+                turtle.right(90)
                 turtle.forward(args.horizontal_finger-args.kerf)
-                turtle.left(90)
+                turtle.right(90)
                 turtle.forward(args.thickness)
                 turtle.right(90)
+                turtle.forward(args.horizontal_finger-args.kerf)
+                turtle.penup()
+                turtle.right(180)
+                turtle.forward(args.horizontal_finger-args.kerf)
             turtle.forward(args.exterior_leg)
-            turtle.right(60)
-        turtle.forward(args.exterior_edge)
-    SHAPES += '<path d="%s"/>\n' % turtle.to_s()
+            turtle.pendown()
+            turtle.left(90)
+            turtle.forward(args.thickness)
+            turtle.right(90)
+            turtle.circle(-args.corner_radius-args.thickness, 60)
+            turtle.right(90)
+            turtle.forward(args.thickness)
+            turtle.right(90)
+            turtle.circle(args.corner_radius, 60)
+            turtle.penup()
+            turtle.right(180)
+            turtle.circle(-args.corner_radius, 60)
+        turtle.forward(args.interior_edge-2*args.corner_inset)
+        turtle.pendown()
+        turtle.left(90)
+        turtle.forward(args.thickness)
+        turtle.right(90)
+        turtle.circle(-args.corner_radius-args.thickness, 60)
+        turtle.right(90)
+        turtle.forward(args.thickness)
+        turtle.right(90)
+        turtle.circle(args.corner_radius, 60)
+        HOLES += '<path d="%s"/>\n' % turtle.to_s()
 
 def draw_side(x0, y0, h, slots):
     global HOLES, SHAPES