add hollow_out_torus

examples/hollow_out/hollow_out_torus.scad

@@ -0,0 +1,22 @@
+use <hull_polyline3d.scad>;
+use <experimental/ptf_torus.scad>;
+use <hollow_out_square.scad>;
+
+width = 5;
+columns = 10;
+rows = 30;
+radius = 30;
+thickness = 2;
+twist = 0;
+
+lines = hollow_out_square([columns, rows], width);
+
+for(line = lines) {  
+   transformed = [for(pt = line) ptf_torus([columns * width, rows * width], pt, [radius, radius / 2], twist = twist)];
+   hull_polyline3d(transformed, thickness, $fn = 4);
+}
+
+color("black")
+rotate_extrude($fn = 36)
+translate([radius * 1.5, 0, 0])
+    circle(radius / 2);