diff --git a/undocumented_features/in_shape_demo.scad b/undocumented_features/in_shape_demo.scad
new file mode 100644
index 00000000..21547bac
--- /dev/null
+++ b/undocumented_features/in_shape_demo.scad
@@ -0,0 +1,32 @@
+include <shape_taiwan.scad>;
+include <in_shape.scad>;
+
+/*    
+points = [
+   [10, 0],
+   [10, 10],
+   [-10, 10], 
+   [-10, -10]
+];*/
+
+
+points = shape_taiwan(30); 
+%polygon(points);
+pt = [-10, 9];
+
+n = 200;
+xs = rands(-10, 10, n);
+ys = rands(-18, 18, n);
+
+pts = [
+    for(i = [0:n]) 
+        let(p = [xs[i], ys[i]]) 
+        if(in_shape(points, p, true))
+        p
+    ]; 
+
+for(p = pts) {
+    translate(p) circle(.2); 
+}
+
+    
\ No newline at end of file
diff --git a/undocumented_features/midpt_smooth_demo.scad b/undocumented_features/midpt_smooth_demo.scad
new file mode 100644
index 00000000..769d0411
--- /dev/null
+++ b/undocumented_features/midpt_smooth_demo.scad
@@ -0,0 +1,14 @@
+include <hull_polyline2d.scad>;
+include <shape_taiwan.scad>;
+include <bijection_offset.scad>;
+include <midpt_smooth.scad>;
+
+
+    
+taiwan = shape_taiwan(100, .5);  
+sm = midpt_smooth(taiwan, 1, true);
+
+*translate([10, 0, 0]) hull_polyline2d(shape_taiwan(100), .1); 
+translate([10, 0, 0]) hull_polyline2d(sm, .1);
+
+echo(len(taiwan));
\ No newline at end of file
diff --git a/undocumented_features/trim_shape_demo.scad b/undocumented_features/trim_shape_demo.scad
new file mode 100644
index 00000000..0112d88e
--- /dev/null
+++ b/undocumented_features/trim_shape_demo.scad
@@ -0,0 +1,14 @@
+include <hull_polyline2d.scad>;
+include <trim_shape.scad>;
+include <shape_taiwan.scad>;
+include <bijection_offset.scad>;
+include <midpt_smooth.scad>;
+
+taiwan = shape_taiwan(50);
+offseted = bijection_offset(taiwan, -2);
+trimmed = trim_shape(offseted, 3, len(offseted) - 6);
+smoothed = midpt_smooth(trimmed, 3);
+
+#hull_polyline2d(taiwan, .1); 
+%translate([25, 0, 0]) hull_polyline2d(offseted, .2);
+hull_polyline2d(smoothed, .1); 
diff --git a/undocumented_features/undocumented_note.md b/undocumented_features/undocumented_note.md
new file mode 100644
index 00000000..80a7bf2a
--- /dev/null
+++ b/undocumented_features/undocumented_note.md
@@ -0,0 +1,18 @@
+voronoi, bend_extrude:
+    https://www.thingiverse.com/thing:3650115
+
+voronoi3d
+    3d version of voronoi, slow but workable
+
+in_shape, in_line
+    in_shape_demo.scad
+
+midpt_smooth
+    midpt_smooth.scad
+
+trim_shape
+    trim_shape_demo.scad
+
+shape_taiwan: new `dt` parameter
+
+bijection_offset: new `epsilon` parameter