diff --git a/examples/beamChain-1.scad b/examples/beamChain-1.scad
index 57d2f07..e4f8e6f 100644
--- a/examples/beamChain-1.scad
+++ b/examples/beamChain-1.scad
@@ -16,7 +16,6 @@ linear_extrude(1){
   // Add some radii to the line transitions
   translate([0,-7,0]){
     radiiPoints=beamPoints(2,1);
-    for(i=[0: len(beamPoints(2,1))]){color("red")translate([radiiPoints[i].x,radiiPoints[i].y,0])cylinder(d=0.2, h=1);}
     polygon(polyRound(beamChain(radiiPoints,offset1=0.02, offset2=-0.02),20));
   }
 
diff --git a/examples/negative-polyRoundExtrude.scad b/examples/negative-polyRoundExtrude.scad
new file mode 100644
index 0000000..365f1d2
--- /dev/null
+++ b/examples/negative-polyRoundExtrude.scad
@@ -0,0 +1,24 @@
+// negative polyRoundExtrude example
+
+include <Round-Anything-1.0.4/polyround.scad>
+
+extrudeRadius = 0.8;
+extrudeHeight = 2;
+tiny = 0.005; // tiny value is used to stop artifacts from planes lining up perfectly
+
+radiiPoints=[
+    [-7, -3,  0 ],
+    [7,  -3,  0 ],
+    [0,  6,   1 ] // top of the triagle is rounded
+];
+negativeRadiiPoints=[
+    [-3, -1,  0 ],
+    [3,  -1,  0 ],
+    [0,  3,   1 ] // top of the triagle is rounded
+];
+
+difference() {
+    polyRoundExtrude(radiiPoints,extrudeHeight, extrudeRadius, extrudeRadius,fn=20);
+    translate([0,0,-tiny])
+        polyRoundExtrude(negativeRadiiPoints,extrudeHeight+2*tiny, -extrudeRadius, -extrudeRadius,fn=20);
+}