diff --git a/cad/display.scad b/cad/display.scad
index 70df92e..a7290fa 100644
--- a/cad/display.scad
+++ b/cad/display.scad
@@ -34,9 +34,8 @@ translate([146.6, 0, 0])
 rpi4_cover();
 
 // hinge test
-translate([100, -80, 0]){
-    male_hinge();
-}
+//translate([width+(thickness*2)/2), -20, 0])
+  //male_hinge();
 
 module usb_compartment(){
   usb_tray_width=31;
@@ -107,22 +106,13 @@ module rpi4_cover(){
     }
 
     // left slope
-    difference(){
-      translate([19+thickness, 0, height+thickness])
-        left_slope(22, depth+(thickness*2), 23.4);
-
-      translate([19+thickness, thickness, height+thickness])
-        left_slope(22, depth, 25);
-    }
+    translate([19+thickness, 0, height+thickness])
+      sloped_walls(22, depth+(thickness*2), 23.4, thickness);
 
     // right slope
-    difference(){
-      translate([145+thickness, 0, height+thickness])
-        right_slope(22, depth+(thickness*2), 23.4);
-
-      translate([145+thickness, thickness, height+thickness])
-        right_slope(22, depth, 25);
-    }
+    translate([145+thickness+22, 0, height+thickness])
+      mirror([1,0,0])
+        sloped_walls(22, depth+(thickness*2), 23.4, thickness);
 
     // logo
     translate([31+thickness+62, (depth+(thickness*2))/2, height+25])
@@ -131,16 +121,24 @@ module rpi4_cover(){
           import(file="mk-logo.svg", center=true);
 }
 
-module left_slope(w, d, h){
+module prism(width, depth, height){
   polyhedron(
-    points=[[0,d,0], [0,0,0], [w,0,0], [w,d,0], [w,d,h], [w,0,h]],
+    points=[[0, depth, 0],
+            [0, 0, 0],
+            [width, 0, 0],
+            [width, depth, 0],
+            [width, depth, height],
+            [width, 0, height]],
     faces=[[0,1,2,3],[5,4,3,2],[0,4,5,1],[0,3,4],[5,2,1]]);
 }
 
-module right_slope(w, d, h){
-  polyhedron(
-    points=[[0,d,0], [0,0,0], [w,0,0], [w,d,0], [0,d,h], [0,0,h]],
-    faces=[[0,1,2,3],[5,4,3,2],[0,4,5,1],[0,3,4],[5,2,1]]);
+module sloped_walls(width, depth, height, thickness){
+  difference(){
+    prism(width, depth, height);
+
+    translate([0, thickness, 0])
+      prism(width, depth-(thickness*2), height);
+  }
 }
 
 module male_hinge(){