diff --git a/tests/extrusions.scad b/tests/extrusions.scad
index dd9a5ba..a431830 100644
--- a/tests/extrusions.scad
+++ b/tests/extrusions.scad
@@ -23,7 +23,7 @@ include <../vitamins/extrusions.scad>
 
 module extrusions()
     layout([for(e = extrusions) extrusion_width(e)], 10)
-        extrusion(extrusions[$i], 80);
+        extrusion(extrusions[$i], 80, cornerHole = extrusion_width(extrusions[$i]) > 20);
 
 if ($preview)
     extrusions();
diff --git a/vitamins/extrusions.scad b/vitamins/extrusions.scad
index 10c2e62..bcb0ddb 100644
--- a/vitamins/extrusions.scad
+++ b/vitamins/extrusions.scad
@@ -20,6 +20,7 @@
 // Extrusion
 //
 //                   W   H    d1   d2   s  cw   cwi    t  st  f
+E1515  = [ "E1515", 15, 15,  2.5,   0,5.7,3.4,  5.7, 1.1,1.1, 0.5 ];
 E2020  = [ "E2020", 20, 20,  4.2,   3,  8,  6, 12.0,   2,  2, 1 ];
 E2040  = [ "E2040", 20, 40,  4.2,   3,  8,  6, 12.0,   2,  2, 1 ];
 E2060  = [ "E2060", 20, 60,  4.2,   3,  8,  6, 12.0,   2,  2, 1 ];
@@ -29,7 +30,7 @@ E3060  = [ "E3060", 30, 60,  6.8, 4.2, 12,  8, 16.5,   2,  2, 1 ];
 E4040  = [ "E4040", 40, 40, 10.5, 6.0, 15, 10, 20.0, 5.5,  3, 1 ];
 E4080  = [ "E4080", 40, 80, 10.5, 6.0, 15, 10, 20.0, 5.5,  3, 1 ];
 
-extrusions = [E2020,E2040,E2060,E2080,E3030,E3060,E4040,E4080];
+extrusions = [E1515,E2020,E2040,E2060,E2080,E3030,E3060,E4040,E4080];
 
 use <extrusion.scad>