diff --git a/nhf/build.py b/nhf/build.py
index 25e957f..dcfbba7 100644
--- a/nhf/build.py
+++ b/nhf/build.py
@@ -39,10 +39,12 @@ class Target:
     def __init__(self,
                  method,
                  name: str,
+                 prototype: bool = False,
                  kind: TargetKind = TargetKind.STL,
                  **kwargs):
         self._method = method
         self.name = name
+        self.prototype = prototype
         self.kind = kind
         self.kwargs = kwargs
     def __str__(self):
diff --git a/nhf/touhou/houjuu_nue/__init__.py b/nhf/touhou/houjuu_nue/__init__.py
index e7c0337..6e3254d 100644
--- a/nhf/touhou/houjuu_nue/__init__.py
+++ b/nhf/touhou/houjuu_nue/__init__.py
@@ -103,6 +103,8 @@ class Parameters(Model):
         track_disk_height=5.0,
         rider_disk_height=7.0,
         radius_axle=8.0,
+        radius_spring=9 + 1.2 * 2,
+        spring_thickness=1.3,
     ))
 
     # Two holes on each side (top and bottom) are used to attach the shoulder
@@ -149,8 +151,8 @@ class Parameters(Model):
     @target(name="trident/handle-insertion")
     def handle_insertion(self):
         return self.trident_handle.insertion()
-    @target(name="trident/proto-handle-terminal-connector")
-    def handle_experimental_connector(self):
+    @target(name="trident/proto-handle-connector", prototype=True)
+    def proto_handle_connector(self):
         return self.trident_handle.one_side_connector(height=15)
     @target(name="trident/handle-terminal-connector")
     def handle_terminal_connector(self):
@@ -305,7 +307,7 @@ class Parameters(Model):
     #def joining_plate(self) -> Cq.Workplane:
     #    return self.wing_joining_plate.plate()
 
-    @target(name="wing_root")
+    @target(name="wing/root")
     def wing_root(self) -> Cq.Assembly:
         """
         Generate the wing root which contains a Hirth joint at its base and a
@@ -320,7 +322,14 @@ class Parameters(Model):
             conn_thickness=self.wing_s0_thickness,
         )
 
-    @target(name="shoulder_joint_parent")
+    @target(name="wing/proto-shoulder-joint-parent", prototype=True)
+    def proto_shoulder_joint_parent(self):
+        return self.shoulder_torsion_joint.track()
+    @target(name="wing/proto-shoulder-joint-child", prototype=True)
+    def proto_shoulder_joint_child(self):
+        return self.shoulder_torsion_joint.rider()
+
+    @target(name="wing/shoulder_joint_parent")
     def shoulder_joint_parent(self) -> Cq.Workplane:
         joint = self.shoulder_torsion_joint
         # Thickness of the lip connecting this joint to the wing root
@@ -365,7 +374,7 @@ class Parameters(Model):
         joint = self.shoulder_torsion_joint
         return self.wing_profile.shoulder_height - 2 * joint.total_height + 2 * joint.rider_disk_height
 
-    @target(name="shoulder_joint_child")
+    @target(name="wing/shoulder_joint_child")
     def shoulder_joint_child(self) -> Cq.Assembly:
         """
         Creates the top/bottom shoulder child joint