add mobius_twins

examples/mobius_twins.scad

@@ -0,0 +1,34 @@
+use <shape_glued2circles.scad>;
+use <ring_extrude.scad>;
+
+$fn = 48;
+r = 100;
+
+module mobius_twins() {
+    a_step = 20;
+    half_a_step = 10;
+    sr = 0.14 * r;
+    half_r = r / 2;
+    
+    module mobius() {
+        difference() {
+            rotate(-a_step)
+            ring_extrude(
+                shape_glued2circles(5, half_r, 35), radius = r, twist = 180
+            );
+            union() {
+                for(angle = [0: a_step: 360 - a_step]) {
+                    rotate([0, 0, angle])
+                    translate([r, 0, 0])
+                    sphere(sr);
+                }
+            }
+        }
+    }
+    
+    mobius();
+    rotate(90) mobius();
+}
+
+mobius_twins();
+