diff --git a/backpack-organization/main-box.scad b/backpack-organization/main-box.scad
index 3f56fc8..67206b3 100644
--- a/backpack-organization/main-box.scad
+++ b/backpack-organization/main-box.scad
@@ -6,7 +6,7 @@ $fn=128;
 outerWall=4;
 innerWall=2;
 layerClearance = 0.5;
-verStr="v11";
+verStr="v12";
 font="Montserrat";
 ep = 0.01; // smallest unit to ensure overlap between shapes
 
@@ -77,6 +77,27 @@ module shellBottom(dims) {
     }
     */
 
+    // ropeway
+    for (i = [1, 3]) {
+      for (j = [-1, 1]) {
+        /* Older, diagonal cut
+        translate([dims[0]/2 - j*dims[0]/2 + j*1.5, i*dims[1]/4, -1])
+        rotate([0, 0, 45 + 90*j])
+        cube([4, 4, bottomShellH + 8]);
+        */
+        translate([dims[0]/2 - j*dims[0]/2 - 1.5, i*dims[1]/4 - 2.5, -1])
+        chamferedCube([3, 5, bottomShellH + 8], chamfer=1.5);
+      }
+
+      /* Older, diagonal cut
+      translate([-1, i*dims[1]/4, 1.5])
+      rotate([-135, 0, 0])
+      cube([dims[0] + 8, 4, 4]);
+      */
+      translate([-1, i*dims[1]/4 - 2.5, -1.5])
+      chamferedCube([dims[0] + 8, 5, 3], chamfer=1.5);
+    }
+
     // version marker
     color("black")
     translate([0.6, 26, 8]) rotate([90, 0,-90])
@@ -132,11 +153,71 @@ module shellTop(dims) {
     }
     */
 
+    // ropeway
+    for (i = [1, 3]) {
+      for (j = [-1, 1]) {
+        /* Older, diagonal cut
+        translate([dims[0]/2 - j*dims[0]/2 + j*1.5, i*dims[1]/4, -1])
+        rotate([0, 0, 45 + 90*j])
+        cube([4, 4, topShellH + 8]);
+        */
+        translate([dims[0]/2 - j*dims[0]/2 - 1.5, i*dims[1]/4 - 2.5, -1])
+        chamferedCube([3, 5, topShellH + 8], chamfer=1.5);
+      }
+
+      /* Older, diagonal cut
+      translate([-1, i*dims[1]/4, 1.5])
+      rotate([-135, 0, 0])
+      cube([dims[0] + 8, 4, 4]);
+      */
+      translate([-1, i*dims[1]/4 - 2.5, -1.5])
+      chamferedCube([dims[0] + 8, 5, 3], chamfer=1.5);
+    }
+
     // version marker
     color("black")
     translate([0.6, 26, 8]) rotate([90, 0,-90])
     linear_extrude(0.61) text(text = verStr, font = font, size = 8);
+
   }
+
+    /* -45 = x + -y
+     * x = y - 45
+     *
+     * 135 = x + y
+     * y = 135 - x
+     * y = 135 - (y - 45)
+     * y = 180 - y
+     * y = 90
+     *
+     */
+
+  // tray indent location
+  //   X: innerWall + iW/2 - audioTraySide/2
+  //      2 + (innerBoxWidth - 2*layerClearance - 2*innerWall)/2 - 64/2
+  //      2 + ((outerBoxWidth - 2*outerWall) - 2*0.5 - 2*2)/2 - 32
+  //      2 + (154 - 8 - 1 - 4)/2 - 32
+  //      40.5
+  //
+  //   Y: innerWall + iL - audioTraySide/2 - cableDia/2 - innerWall
+  //      2 + (innerBoxLength - 2*layerClearance - 2*innerWall) - 64/2 - 130/2 - 2
+  //      2 + (outerBoxLength - 2*outerWall) - 2*0.5 - 2*2 - 32 - 65 - 2
+  //      300 - 8 - 1 - 4 - 32 - 65
+  //      190
+  //
+  translate([
+    40.5 + outerWall + layerClearance,
+    190 + outerWall + layerClearance,
+    1])
+    //(dims[0] - audioTraySide)/2,
+    //dims[1] - outerWall - innerWall - audioTraySide/2 - 130/2,
+    //1])
+  roundedCube(
+    [ audioTraySide - 2*(innerWall + layerClearance),
+      audioTraySide - 2*(innerWall + layerClearance),
+      4],
+    [1, 1, 1]);
+
 }
 
 module layer1() {
@@ -544,9 +625,8 @@ standoffX = outerBoxWidth + 10;
 standoffY = outerBoxLength + 10;
 
 // test-print the lip
-shellBottom([20, 30, 30]);
-translate([24, 0, 0]) shellTop([20, 30, 30]);
-/*
+// shellBottom([20, 30, 30]);
+// translate([24, 0, 0]) shellTop([20, 30, 30]);
 shellBottom([outerBoxWidth, outerBoxLength, outerBoxHeight]);
 translate([0, standoffY, 0]) shellTop([outerBoxWidth, outerBoxLength, outerBoxHeight]);
 translate([standoffX, 0, 0]) layer1();
@@ -555,4 +635,3 @@ translate([2*standoffX, 0, 0]) audioJackTray();
 translate([2*standoffX, 80, 0]) usbBitsTray();
 translate([2*standoffX, 160, 0]) headphoneAmpTray();
 translate([2*standoffX, 240, 0]) drumKeyTray();
-*/