diff --git a/README.md b/README.md
index f7ccb47..7d5faed 100644
--- a/README.md
+++ b/README.md
@@ -5,7 +5,24 @@ This library is a set of useful tools, shapes and manipulators that I developed
 projects, including large ones like the Snappy-Reprap printed 3D printer.
 
 # Overview
+The library files are as follows:
+  - ```transforms.scad```: The most commonly used transformations, manipulations, and shortcuts are in this file.
+  - ```shapes.scad```: Common useful shapes and structured objects.
+  - ```masks.scad```: Shapes that are useful for masking with ```difference()``` and ```intersect()```.
+  - ```paths.scad```: Functions and modules to work with arbitrary 3D paths.
+  - ```bezier.scad```: Functions and modules to work with bezier curves.
+  - ```involute_gears.scad```: Modules and functions to make involute gears and racks.
+  - ```metric_screws.scad```: Functions and modules to make holes for metric screws and nuts.
+  - ```joiners.scad```: Modules to make joiner shapes for connecting separately printed objects.
+  - ```sliders.scad```: Modules for creating simple sliders and rails.
+  - ```acme_screws.scad```: Modules to make trapezoidal (ACME) threaded rods and nuts.
+  - ```nema_steppers.scad```: Modules to make mounting holes for NEMA motors.
+  - ```linear_bearings.scad```: Modules to make mounts for LMxUU style linear bearings.
+  - ```wiring.scad```: Modules to render routed bundles of wires.
+  - ```math.scad```: Useful helper functions and constants.
+  - ```quaternions.scad```: Functions to work with quaternion rotations.
 
+## transforms.scad
 The most commonly useful of the library files is ```transforms.scad```.  It provides features such as:
   - ```up()```, ```down()```, ```left()```, ```right()```, ```fwd()```, ```back()``` as more readable alternatives to ```translate()```.
   - ```xrot()```, ```yrot()```, ```zrot()``` as single-axis alternatives to ```rotate```.
@@ -15,6 +32,7 @@ The most commonly useful of the library files is ```transforms.scad```.  It prov
   - Easy mirroring with ```xflip()```, ```xflip_copy()```, etc.
   - Slice items in half with ```top_half()```, ```left_half()```, ```back_half()```, etc.
 
+## shapes.scad
 The ```shapes.scad``` library file provides useful compound shapes, such as:
   - ```upcube()``` a ridiculously useful version of ```cube()``` that is centered on top of the XY plane.
   - Filleted (rounded) and Chamferred (bevelled) cubes and cylinders.
@@ -27,3 +45,15 @@ The ```shapes.scad``` library file provides useful compound shapes, such as:
   - ```thinning_triangle()``` makes a right triangle which thins in the middle, to reduce print volume.
   - ```sparse_strut()``` makes a cross-braced open strut wall, optimized for support-less 3D printing.
   - ```corrugated_wall()``` makes a corrugated wall to reduce print volume while keeping strength.
+
+## masks.scad
+The ```masks.scad``` library file provides mask shapes like:
+  - ```angle_pie_mask()``` to mask a pie-slice shape.
+  - ```chamfer_mask_x()```, ```chamfer_mask_y()```, and ```chamfer_mask_z()``` to chamfer (bevel) an axis aligned 90 degree edge.
+  - ```fillet_mask_x()```, ```fillet_mask_y()```, and ```fillet_mask_z()``` to fillet (round) an axis aligned 90 degree edge.
+  - ```fillet_corner_mask()``` to fillet a 90 degree corner.
+  - ```fillet_angled_edge_mask()``` to fillet an acute or obtuse vertical edge.
+  - ```fillet_angled_corner_mask()``` to fillet the corner of two acute or obtuse planes.
+  - ```fillet_cylinder_mask()``` to fillet the end of a cylinder.
+  - ```fillet_hole_mask()``` to fillet the edge of a cylindrical hole.
+  
\ No newline at end of file
diff --git a/acme_screw.scad b/acme_screws.scad
similarity index 98%
rename from acme_screw.scad
rename to acme_screws.scad
index f1ed557..40c13c4 100644
--- a/acme_screw.scad
+++ b/acme_screws.scad
@@ -1,5 +1,5 @@
 //////////////////////////////////////////////////////////////////////
-// Square-threaded (ACME) Screw Rods and Nuts
+// Trapezoidal-threaded (ACME) Screw Rods and Nuts
 //////////////////////////////////////////////////////////////////////
 
 /*
diff --git a/masks.scad b/masks.scad
index 87d5288..1eb69ca 100644
--- a/masks.scad
+++ b/masks.scad
@@ -32,6 +32,7 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 
 include <transforms.scad>
+include <math.scad>
 
 
 module angle_half_pie_mask(
@@ -202,6 +203,9 @@ module fillet_mask(h=1.0, r=1.0, center=true)
 		);
 	}
 }
+module fillet_mask_z(l=1.0, r=1.0) fillet_mask(h=l, r=r, center=true);
+module fillet_mask_y(l=1.0, r=1.0) xrot(90) fillet_mask(h=l, r=r, center=true);
+module fillet_mask_x(l=1.0, r=1.0) yrot(90) fillet_mask(h=l, r=r, center=true);
 
 
 // Creates a vertical mask that can be used to fillet the edge where two
@@ -213,8 +217,9 @@ module fillet_mask(h=1.0, r=1.0, center=true)
 //   ang = angle that the planes meet at.
 //   center = If true, vertically center mask.
 // Example:
-//   fillet_planes_joint_mask(h=50.0, r=10.0, ang=120, $fn=32);
-module fillet_planes_joint_mask(h=1.0, r=1.0, ang=90, center=true)
+//   fillet_angled_edge_mask(h=50.0, r=10.0, ang=120, $fn=32);
+//   fillet_angled_edge_mask(h=50.0, r=10.0, ang=30, $fn=32);
+module fillet_angled_edge_mask(h=1.0, r=1.0, ang=90, center=true)
 {
 	sweep = 180-ang;
 	n = ceil(segs(r)*sweep/360);
@@ -240,8 +245,8 @@ module fillet_planes_joint_mask(h=1.0, r=1.0, ang=90, center=true)
 //   fillet = radius of the fillet.
 //   ang = angle between planes that you need to fillet the corner of.
 // Example:
-//   fillet_edge_joint_mask(fillet=100, ang=90);
-module fillet_edge_joint_mask(fillet=1.0, ang=90)
+//   fillet_angled_corner_mask(fillet=100, ang=90);
+module fillet_angled_corner_mask(fillet=1.0, ang=90)
 {
 	dy = fillet * tan(ang/2);
 	th = max(dy, fillet*2);
@@ -280,9 +285,9 @@ module fillet_edge_joint_mask(fillet=1.0, ang=90)
 //     translate([0, 5, 8]) yrot(90) fillet_mask(h=7, r=3);
 //     translate([3, 0, 8]) xrot(90) fillet_mask(h=11, r=3);
 //     translate([3, 5, 0]) fillet_mask(h=17, r=3);
-//     translate([3, 5, 8]) corner_fillet_mask(r=3);
+//     translate([3, 5, 8]) fillet_corner_mask(r=3);
 //   }
-module corner_fillet_mask(r=1.0)
+module fillet_corner_mask(r=1.0)
 {
 	difference() {
 		cube(size=r*2, center=true);
@@ -291,7 +296,7 @@ module corner_fillet_mask(r=1.0)
 		}
 	}
 }
-//!corner_fillet_mask(r=10.0);
+//!fillet_corner_mask(r=10.0);
 
 
 // Create a mask that can be used to round the end of a cylinder.
diff --git a/shapes.scad b/shapes.scad
index 957fff5..e310ac6 100644
--- a/shapes.scad
+++ b/shapes.scad
@@ -351,6 +351,32 @@ module trapezoid(size1=[1,1], size2=[1,1], h=1, center=false)
 }
 
 
+// Makes a teardrop shape in the XZ plane. Useful for 3D printable holes.
+//   r = radius of circular part of teardrop.  (Default: 1)
+//   h = thickness of teardrop. (Default: 1)
+// Example:
+//   teardrop(r=3, h=2, ang=30);
+module teardrop(r=1, h=1, ang=45, $fn=undef)
+{
+	$fn = ($fn==undef)?max(12,floor(180/asin(1/r)/2)*2):$fn;
+	xrot(90) union() {
+		translate([0, r*sin(ang), 0]) {
+			scale([1, 1/tan(ang), 1]) {
+				difference() {
+					zrot(45) {
+						cube(size=[2*r*cos(ang)/sqrt(2), 2*r*cos(ang)/sqrt(2), h], center=true);
+					}
+					translate([0, -r/2, 0]) {
+						cube(size=[2*r, r, h+1], center=true);
+					}
+				}
+			}
+		}
+		cylinder(h=h, r=r, center=true);
+	}
+}
+
+
 // Created a sphere with a conical hat, to make a 3D teardrop.
 //   r = radius of spherical portion of the bottom. (Default: 1)
 //   d = diameter of spherical portion of bottom. (Use instead of r)
@@ -495,32 +521,6 @@ module arced_slot(
 }
 
 
-// Makes a teardrop shape in the XZ plane. Useful for 3D printable holes.
-//   r = radius of circular part of teardrop.  (Default: 1)
-//   h = thickness of teardrop. (Default: 1)
-// Example:
-//   teardrop(r=3, h=2, ang=30);
-module teardrop(r=1, h=1, ang=45, $fn=undef)
-{
-	$fn = ($fn==undef)?max(12,floor(180/asin(1/r)/2)*2):$fn;
-	xrot(90) union() {
-		translate([0, r*sin(ang), 0]) {
-			scale([1, 1/tan(ang), 1]) {
-				difference() {
-					zrot(45) {
-						cube(size=[2*r*cos(ang)/sqrt(2), 2*r*cos(ang)/sqrt(2), h], center=true);
-					}
-					translate([0, -r/2, 0]) {
-						cube(size=[2*r, r, h+1], center=true);
-					}
-				}
-			}
-		}
-		cylinder(h=h, r=r, center=true);
-	}
-}
-
-
 // Makes a rectangular strut with the top side narrowing in a triangle.
 // The shape created may be likened to an extruded home plate from baseball.
 // This is useful for constructing parts that minimize the need to support