diff --git a/pref-battholder-openscad/pref-assembly-20240112-BattHolder1-reexport.stl b/pref-battholder-openscad/pref-assembly-20240112-BattHolder1-reexport.stl
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diff --git a/pref-battholder-openscad/pref-battholder-countersink-prod-a.stl b/pref-battholder-openscad/pref-battholder-countersink-prod-a.stl
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diff --git a/pref-battholder-openscad/pref-battholder-countersink-prod-b.stl b/pref-battholder-openscad/pref-battholder-countersink-prod-b.stl
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index 0000000..679490a
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diff --git a/pref-battholder-openscad/pref-battholder-countersink.scad b/pref-battholder-openscad/pref-battholder-countersink.scad
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--- /dev/null
+++ b/pref-battholder-openscad/pref-battholder-countersink.scad
@@ -0,0 +1,18 @@
+mirror([0,0,0]) union() {
+    difference() {
+        rotate([-90,0,0]) import("pref-assembly-20240112-BattHolder1-reexport.stl");
+
+        // countersinks
+        translate([-35.5, -8.5, -2.3])
+        cylinder(h = 1.2, r = 3.8/2, $fn = 20);
+        translate([17.7, -8.5, -2.3])
+        cylinder(h = 1.2, r = 3.8/2, $fn = 20);
+        
+        // cut off a bit
+        translate([-39, -13, -4]) cube([60,2,4]);
+    }
+
+    // left and right extensions
+    translate([19.7, -11, -3.5])
+    cube([0.5,7.5,2]);
+}
\ No newline at end of file