diff --git a/3d-printing/files/scad/head_cap.scad b/3d-printing/files/scad/head_cap.scad
index de807b5..851bc87 100644
--- a/3d-printing/files/scad/head_cap.scad
+++ b/3d-printing/files/scad/head_cap.scad
@@ -11,4 +11,9 @@ translate([1,1,-1]) minkowski()
   cube([40-2,14-2,2]);
   cylinder(r=2.2,h=10);
 }
+
+difference(){
+translate([40/2,14/2,11-.5])cylinder(d = 5.5,  h = 8); 
+translate([40/2,14/2,11-1])cube([5.5,4,4],center=true);
+}
 }
\ No newline at end of file