diff --git a/nhf/touhou/shiki_eiki/crown.py b/nhf/touhou/shiki_eiki/crown.py
index 2dcb300..7e8f7ad 100644
--- a/nhf/touhou/shiki_eiki/crown.py
+++ b/nhf/touhou/shiki_eiki/crown.py
@@ -22,6 +22,8 @@ class Crown(Model):
     side_guard_thickness: float = 15.0
     side_guard_channel_radius: float = 90
     side_guard_channel_height: float = 10
+    side_guard_hole_height: float = 15.0
+    side_guard_hole_diam: float = 1.5
 
     material: Material = Material.METAL_BRASS
     material_side: Material = Material.PLASTIC_PLA
@@ -356,7 +358,24 @@ class Crown(Model):
             )
         return sketch.assemble()
 
-    def side_guard(self) -> Cq.Workplane:
+    def side_guard_dovetail(self) -> Cq.Solid:
+        """
+        Generates a dovetail coupling for the side guard
+        """
+        dx = self.side_guard_thickness / 2
+        wire = Cq.Wire.makePolygon([
+            (dx * 0.5, 0),
+            (dx * 0.8, dx),
+            (-dx * 0.8, dx),
+            (-dx * 0.5, 0),
+        ], close=True)
+        return Cq.Solid.extrudeLinear(
+            wire,
+            [],
+            (0,0,self.height/3),
+        )
+
+    def side_guard(self, attach_left: bool = True, attach_right: bool = False) -> Cq.Workplane:
         """
         Constructs the side guard using a cone. Via Gauss's Theorema Egregium,
         the surface of the cone can be deformed into a plane.
@@ -374,11 +393,8 @@ class Crown(Model):
             height=self.height,
             angleDegrees=angle,
         )
-        shell = (
-            outer.cut(inner)
-            .rotate((0,0,0), (0,0,1), -angle/2)
-        )
-        dx = math.sin(math.radians(angle / 2)) * self.radius_middle
+        shell = (outer - inner).rotate((0,0,0), (0,0,1), -angle/2)
+        dx = math.sin(math.radians(angle / 2)) * (self.radius_middle + self.side_guard_thickness)
         profile = (
             Cq.Workplane('YZ')
             .polyline([
@@ -401,7 +417,24 @@ class Crown(Model):
                 height=self.side_guard_channel_height,
             )
         )
-        return shell * profile - channel
+        result = shell * profile - channel
+        for i in [-2, -1, 0, 1, 2]:
+            phi = i * (math.pi / 14)
+            hole = Cq.Solid.makeCylinder(
+                radius=self.side_guard_hole_diam / 2,
+                height=self.radius_upper * 2,
+                pnt=(0, 0, self.side_guard_hole_height),
+                dir=(math.cos(phi), math.sin(phi), 0),
+            )
+            result = result - hole
+
+        radius_attach = self.radius_lower + self.side_guard_thickness / 2
+        # tilt the dovetail by radius differential
+        angle_tilt = math.degrees(math.atan2(self.radius_middle - self.radius_lower, self.height / 2))
+        print(angle_tilt)
+        dovetail = self.side_guard_dovetail()
+        loc_dovetail = Cq.Location.rot2d(angle / 2) * Cq.Location(radius_attach, 0, 0, 0, angle_tilt, 0) * Cq.Location.rot2d(180)
+        return result - dovetail.moved(loc_dovetail)
 
     def front_surrogate(self) -> Cq.Workplane:
         """