diff --git a/nhf/build.py b/nhf/build.py
index 106577c..4d4c6c2 100644
--- a/nhf/build.py
+++ b/nhf/build.py
@@ -90,7 +90,7 @@ class Target:
                 x = (
                     Cq.Workplane()
                     .add(x._faces)
-                    .add(x._wires)
+                    .add(x.wires)
                     .add(x._edges)
                 )
             assert isinstance(x, Cq.Workplane)
diff --git a/nhf/tool/light_panel.py b/nhf/tool/light_panel.py
index 86d9983..631637f 100644
--- a/nhf/tool/light_panel.py
+++ b/nhf/tool/light_panel.py
@@ -14,7 +14,7 @@ class LightPanel(Model):
     width: float = 200.0
 
     grid_height: float = 30.0
-    grid_top_height: float = 10.0
+    grid_top_height: float = 5.0
     # Distance from grid to edge
     grid_margin: float = 20.0
     # Number of holes in each row of the grid
@@ -23,7 +23,7 @@ class LightPanel(Model):
     grid_hole_width: float = 15.0
 
     base_thickness: float = 25.4/16
-    grid_thickness: float = 25.4/8
+    grid_thickness: float = 25.4/4
     base_material: Material = Material.WOOD_BIRCH
     grid_material: Material = Material.ACRYLIC_TRANSPARENT
 
@@ -68,9 +68,11 @@ class LightPanel(Model):
 
     @submodel(name="base")
     def base(self) -> MountingBox:
+        xshift = self.length / 2 - self.controller.length - self.grid_margin / 2
+        yshift = self.grid_margin / 2
         holes = [
             Hole(
-                x=x, y=y,
+                x=x + xshift, y=y + yshift,
                 diam=self.controller.hole_diam,
                 tag=f"controller_conn{i}",
             )
@@ -96,9 +98,9 @@ class LightPanel(Model):
             )
         )
         # Grid thickness t is fixed, so the spacing of the grid satisfies
-        # margin + t + (n-1) * (t + spacing) + margin = width
-        spacing = (self.width - 2 * self.grid_margin - self.grid_thickness) / (self.grid_layers - 1) - self.grid_thickness
-        shift = self.grid_margin + self.grid_thickness * 2
+        # margin + t + (n-1) * spacing + margin = width
+        spacing = (self.width - 2 * self.grid_margin - self.grid_thickness) / (self.grid_layers - 1)
+        shift = self.grid_margin + self.grid_thickness / 2
         for i in range(self.grid_layers):
             assembly = assembly.addS(
                 self.grid(),