From ed205d713ff894097614752b809332ccbeb6d928 Mon Sep 17 00:00:00 2001
From: Adrian Mariano <avm4@cornell.edu>
Date: Thu, 13 Feb 2020 18:28:26 -0500
Subject: [PATCH] added mobius strip

---
 skin.scad | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/skin.scad b/skin.scad
index 7e87a58..b2fd237 100644
--- a/skin.scad
+++ b/skin.scad
@@ -289,6 +289,11 @@ include <vnf.scad>
 //       for (ang = [0:10:90])
 //       rot([0,ang,0], cp=[200,0,0], p=path3d(circle(d=100,$fn=12-(ang/10))))
 //   ],method="distance",slices=10,refine=10);
+// Example(FlatSpin): Möbius Strip.  This is a tricky model because when you work your way around to the connection, the direction of the profiles is flipped, so how can the proper geometry be created?  The trick is to duplicate the first profile and turn the caps off.  The model closes up and forms a valid polyhedron.  
+//   skin([
+//     for (ang = [0:5:360])
+//     rot([0,ang,0], cp=[100,0,0], p=rot(ang/2, p=path3d(square([1,30],center=true))))
+//   ], caps=false, slices=0, refine=20);
 // Example: If you create a self-intersecting polyhedron the result is invalid.  In some cases self-intersection may be obvous.  Here is a more subtle example. 
 //   skin([
 //          for (a = [0:30:180]) let(