diff --git a/3D_Models/Holder.scad b/3D_Models/Holder.scad
--- a/3D_Models/Holder.scad
+++ b/3D_Models/Holder.scad
@@ -13,7 +13,8 @@ ring_12_inner_diameter = 23.3 - 0.5;
 ring_thickness = 6.7;
 ring_z_offset = neopixel_holder_thickness - ring_thickness;
 
-channel_length = overall_outer_diameter-3;
+//channel_length = overall_outer_diameter-3;
+channel_length = ring_12_outer_diameter;
 
 alignment_pin_position = (-overall_outer_diameter/2) + 1.5; 
 
@@ -27,10 +28,19 @@ module ring(h, od, id) {
 };
 
 module channel() {    
-    translate([-(channel_length/2), -2, ring_z_offset]) cube([channel_length, 4, ring_thickness+1]);
+    translate([-(channel_length/2)-8, -2, ring_z_offset]) cube([channel_length+2, 4, ring_thickness+1]);
+    rotate([0, 0, 37.5]) translate([15, -2, ring_z_offset]) cube([15, 4, ring_thickness+1]);
+    rotate([0, 0, -37.5]) translate([15, -2, ring_z_offset]) cube([15, 4, ring_thickness+1]);
     translate([0, 0, -1]) cylinder(h=neopixel_holder_thickness+2, d=10);
 };
 
+module alignment_pin() {
+    for (x=[0, 1])
+      mirror([x, 0, 0])
+        translate([alignment_pin_position, -(4-0.2)/2, ring_z_offset])
+          cube([3, 4-0.2, neopixel_holder_thickness - ring_z_offset + 0.1]);
+}
+
 module neopixel_holder() {
     
     difference () {
@@ -40,8 +50,8 @@ module neopixel_holder() {
         for (d=[[ring_24_outer_diameter, ring_24_inner_diameter], [ring_12_outer_diameter, ring_12_inner_diameter]])
             translate([0, 0, ring_z_offset])
                 ring(h=ring_thickness+1, od=d[0], id=d[1]);
-        
         channel();
+        alignment_pin();
     }
 };
 
@@ -53,5 +63,6 @@ module translucent_disk() {
                 cube([3, 4-0.2, neopixel_holder_thickness -ring_z_offset]);
 };
 
-translate([-(overall_outer_diameter/2+1), 0, 0]) neopixel_holder();
-translate([(overall_outer_diameter/2+1), 0, 0]) translucent_disk();
\ No newline at end of file
+neopixel_holder();
+// translate([-(overall_outer_diameter/2+1), 0, 0]) neopixel_holder();
+//translate([(overall_outer_diameter/2+1), 0, 0]) translucent_disk();