diff --git a/x-pack-18-battery.scad b/x-pack-18-battery.scad
new file mode 100644
index 0000000..9284a44
--- /dev/null
+++ b/x-pack-18-battery.scad
@@ -0,0 +1,52 @@
+$fn=50;
+
+dims = [74, 24.5, 6.3];
+
+module screwpost(h) {
+  //  2.7d, 3.5h over lip
+  difference() {
+    cylinder(d=2.7, h=h);
+    cylinder(d=1.7, h=h);
+  }
+}
+
+union() {
+  difference() {
+    union() {
+      cube(dims);
+      // outer lock
+      translate([0, -2.5, 1]) {
+        difference() {
+          cube([6, 29.5, 3]);
+          translate([1, 1.5, 1.01])
+            cube([6, 26.5, 2]);
+        }
+      }
+      // center fins
+      translate([39.7, -2.25, 1])
+        cube([6.8, 29, 1]);
+    }
+    // inside
+    translate([1,1,1])
+      cube(dims - [2,2,0]);
+    // lip
+    translate([0.5,0.5,dims.z - 1])
+      cube(dims - [1, 1, 0]);
+    // pcb slot
+    translate([dims.x - 3.7, 0.5, 1])
+      cube([2.7, dims.y - 1, dims.z]);
+  }
+  // battery connector lip
+  translate([dims.x - 1, dims.y - 10, 0])
+    cube([1,6.7,8]);
+
+  translate([3.35, 3.35, 0])
+    screwpost(10.25);
+  translate([3.35, dims.y - 3.35, 0])
+    screwpost(10.25);
+
+  translate([dims.x - 3.35 - 2.7, 3.35, 0])
+    screwpost(8);
+  translate([dims.x - 3.35 - 2.7, dims.y - 3.35, 0])
+    screwpost(8);
+}