diff --git a/nhf/parts/box.py b/nhf/parts/box.py
index 109c667..7d2cbff 100644
--- a/nhf/parts/box.py
+++ b/nhf/parts/box.py
@@ -54,6 +54,7 @@ class MountingBox(Model):
 
     generate_side_tags: bool = True
 
+    # Determines the position of side tags
     flip_y: bool = False
 
     @target(kind=TargetKind.DXF)
diff --git a/nhf/touhou/houjuu_nue/__init__.py b/nhf/touhou/houjuu_nue/__init__.py
index af76e05..6f8347c 100644
--- a/nhf/touhou/houjuu_nue/__init__.py
+++ b/nhf/touhou/houjuu_nue/__init__.py
@@ -62,16 +62,15 @@ class Parameters(Model):
     wing_l1: MW.WingL = field(default_factory=lambda: MW.WingL(
         name="l1",
         wrist_angle=-45.0,
-        shoulder_joint=MJ.ShoulderJoint(directrix_id=1),
     ))
     wing_l2: MW.WingL = field(default_factory=lambda: MW.WingL(
         name="l2",
         wrist_angle=-30.0,
+        shoulder_joint=MJ.ShoulderJoint(directrix_id=1),
     ))
     wing_l3: MW.WingL = field(default_factory=lambda: MW.WingL(
         name="l3",
         wrist_angle=0.0,
-        shoulder_joint=MJ.ShoulderJoint(directrix_id=1),
     ))
 
     trident: MT.Trident = field(default_factory=lambda: MT.Trident())
diff --git a/nhf/touhou/houjuu_nue/joints.py b/nhf/touhou/houjuu_nue/joints.py
index 7840715..246dfa2 100644
--- a/nhf/touhou/houjuu_nue/joints.py
+++ b/nhf/touhou/houjuu_nue/joints.py
@@ -570,7 +570,7 @@ class DiskJoint(Model):
 
 
 @dataclass(kw_only=True)
-class ElbowJoint:
+class ElbowJoint(Model):
     """
     Creates the elbow and wrist joints.
 
@@ -629,6 +629,7 @@ class ElbowJoint:
         r = self.parent_arm_radius
         return [r - dx, r + dx]
 
+    @target(name="child")
     def child_joint(self) -> Cq.Assembly:
         angle = -self.disk_joint.tongue_span / 2
         dz = self.disk_joint.disk_thickness / 2
@@ -646,9 +647,11 @@ class ElbowJoint:
         )
         return result
 
+    @target(name="parent-lower")
     def parent_joint_lower(self) -> Cq.Workplane:
         return self.disk_joint.housing_lower()
 
+    @target(name="parent-upper")
     def parent_joint_upper(self):
         axial_offset = Cq.Location((self.parent_arm_radius, 0, 0))
         housing_dz = self.disk_joint.housing_upper_dz
@@ -683,6 +686,7 @@ class ElbowJoint:
         )
         return result
 
+    @assembly()
     def assembly(self, angle: float = 0) -> Cq.Assembly:
         result = (
             Cq.Assembly()
diff --git a/nhf/touhou/houjuu_nue/wing.py b/nhf/touhou/houjuu_nue/wing.py
index e7e352e..86ec226 100644
--- a/nhf/touhou/houjuu_nue/wing.py
+++ b/nhf/touhou/houjuu_nue/wing.py
@@ -635,6 +635,10 @@ class WingProfile(Model):
         result = (
             Cq.Assembly()
         )
+        tag_top, tag_bot = "top", "bot"
+        if self.flip:
+            tag_top, tag_bot = tag_bot, tag_top
+
         if "s0" in parts:
             result.add(self.assembly_s0(), name="s0")
         if "shoulder" in parts:
@@ -642,20 +646,18 @@ class WingProfile(Model):
         if "s0" in parts and "shoulder" in parts:
             (
                 result
-                .constrain("s0/shoulder?conn_top0", "shoulder/parent_top/lip?conn0", "Plane")
-                #.constrain("s0/shoulder?conn_top1", "shoulder/parent_top/lip?conn1", "Plane")
-                .constrain("s0/shoulder?conn_bot0", "shoulder/parent_bot/lip?conn0", "Plane")
-                #.constrain("s0/shoulder?conn_bot1", "shoulder/parent_bot/lip?conn1", "Plane")
+                .constrain(f"s0/shoulder?conn_top0", f"shoulder/parent_{tag_top}/lip?conn0", "Plane")
+                .constrain(f"s0/shoulder?conn_bot0", f"shoulder/parent_{tag_bot}/lip?conn0", "Plane")
             )
         if "s1" in parts:
             result.add(self.assembly_s1(), name="s1")
         if "s1" in parts and "shoulder" in parts:
             (
                 result
-                .constrain("s1/shoulder_top?conn0", "shoulder/child/lip_top?conn0", "Plane")
-                .constrain("s1/shoulder_top?conn1", "shoulder/child/lip_top?conn1", "Plane")
-                .constrain("s1/shoulder_bot?conn0", "shoulder/child/lip_bot?conn0", "Plane")
-                .constrain("s1/shoulder_bot?conn1", "shoulder/child/lip_bot?conn1", "Plane")
+                .constrain("s1/shoulder_top?conn0", f"shoulder/child/lip_{tag_top}?conn0", "Plane")
+                .constrain("s1/shoulder_top?conn1", f"shoulder/child/lip_{tag_top}?conn1", "Plane")
+                .constrain("s1/shoulder_bot?conn0", f"shoulder/child/lip_{tag_bot}?conn0", "Plane")
+                .constrain("s1/shoulder_bot?conn1", f"shoulder/child/lip_{tag_bot}?conn1", "Plane")
             )
         if "elbow" in parts:
             result.add(self.elbow_joint.assembly(angle=angle_elbow_wrist), name="elbow")