diff --git a/boxes/generators/wallrack.py b/boxes/generators/wallrack.py
index 4649c42a..d33b499c 100644
--- a/boxes/generators/wallrack.py
+++ b/boxes/generators/wallrack.py
@@ -41,28 +41,31 @@ def __init__(self):
         self.argparser.add_argument(
             "--back_height",  action="store", type=float, default=1.5,
             help="height of the back as fraction of the front height")
+        self.argparser.add_argument(
+            "--side_edges", action="store",
+            type=ArgparseEdgeType("Fh"), choices=list("Fh"),
+            default="h", help="edge type holding the shelfs together")
         self.argparser.add_argument(
             "--flat_bottom", type=boolarg, default=False, help="Make bottom Flat, so that the rack can also stand")
 
     def generate_shelves(self, x, y, front_height, back_height):
+        se = self.side_edges
         for i in range(len(self.sh)):
             self.rectangularWall(x, y, "ffff", move="up", label=f"shelf {i+1}")
-            self.rectangularWall(x, front_height, "Ffef", move="up", label=f"front lip {i+1}")
-            self.trapezoidWall(y, front_height, back_height, "FfeF", move="right", label=f"right lip {i+1}")
-            self.trapezoidWall(y, front_height, back_height, "FfeF", move="up", label=f"left lip {i+1}")
+            self.rectangularWall(x, front_height, se + "fef", move="up", label=f"front lip {i+1}")
+            self.trapezoidWall(y, front_height, back_height, se + "fe" + se, move="right", label=f"right lip {i+1}")
+            self.trapezoidWall(y, front_height, back_height, se + "fe" + se, move="up", label=f"left lip {i+1}")
             self.move(y + self.thickness*2, back_height, "left", before=True)
 
     #Generate finger holes for back part
     def generate_finger_holes(self, x, back_height):
         t = self.thickness
-        offset = -self.sh[0] + (0 if self.flat_bottom else t)
-        for i in self.sh:
-            offset += i
-            pos_y = offset
-            self.fingerHolesAt(t*0.5, pos_y, x, 0)
-            pos_y += t*0.5
-            self.fingerHolesAt(0, pos_y, back_height, 90)
-            self.fingerHolesAt(x+t, pos_y, back_height, 90)
+        pos_y = 0
+        for h in self.sh:
+            self.fingerHolesAt(t*0.5, pos_y + 0.5*t, x, 0)
+            self.fingerHolesAt(0, pos_y + t, back_height, 90)
+            self.fingerHolesAt(x+t, pos_y + t, back_height, 90)
+            pos_y += h
 
     def render(self):
         x, y, front_height = self.x, self.y, self.wall_height
@@ -78,6 +81,7 @@ def render(self):
         else:
             total_height = sum(self.sh[:-1]) + back_height
 
-        self.rectangularWall(x+self.thickness, total_height, "EE" + self.top_edge + "E",
+        be = "e" if self.flat_bottom and self.side_edges == "F" else "E"
+        self.rectangularWall(x+self.thickness, total_height, be + "E" + self.top_edge + "E",
                              callback=[partial(self.generate_finger_holes, x, back_height)], label="back wall", move="right")
         self.generate_shelves(x, y, front_height, back_height)