diff --git a/Arches/arches.scad b/Arches/arches.scad
new file mode 100755
index 0000000..c21addc
--- /dev/null
+++ b/Arches/arches.scad
@@ -0,0 +1,54 @@
+// file arches.scad
+// Creates Gothic or circular arches, made up of smaller "stones
+// (c) 2020 Rich Cameron
+// released under a Creative Commons CC-BY 4.0 International License
+
+size = 80; //diameter of the arch opening at the base, mm
+w = 10; //width of the bricks that make the arch, mm
+thick = w; //height of the print, set to 0 for 2D printing on paper
+segments = 11; // Number of stones; use 10.01 for a small keystone (the stone on top of a Gothic arch)
+gap = 0.1; //Gap between stones (to leave space for mortar, for example), mm
+separate = 0; //Extra spacing between the stones for printing (to ensure that they don't stick together).
+
+gothic = false; //Make this true to print a Gothic arch, false for a circular one 
+
+$fs = .2;
+$fa = 2;
+	
+
+if(thick) linear_extrude(thick) {
+	arch();
+} else {
+	arch();
+}
+
+
+module arch() {
+	if(gothic) for(i = [0:segments / 2 - .0001], j = [0, 1]) mirror([j, 0, 0]) translate([separate * (floor((segments / 2 - .0001)) - i), separate * i, 0]) intersection() {
+		difference() {
+			translate([-size / 2, 0, 0]) circle(size + w);
+			translate([-size / 2, 0, 0]) circle(size);
+		}
+		square(size + w);
+		if(segments > 1) offset(-gap / 2) translate([-size / 2, 0, 0]) rotate(120 / segments * i) intersection() {
+			square(size + w * 2);
+			if((segments % 2) || (i < (segments / 2 - 1))) rotate(-90 + 120 / segments) square(size + w * 2);
+			else rotate(-120 / segments * i) translate([size / 2, 0, 0]) square(size + w);
+		}
+	} else for(i = [0:segments / 2 - .0001], j = [0, 1]) mirror([j, 0, 0]) translate([separate * (floor((segments / 2 - .0001)) - i), separate * i, 0])intersection() {
+		difference() {
+			circle(size / 2 + w);
+			circle(size / 2);
+		}
+		square(size + w);
+		if(segments > 1) offset(-gap / 2) rotate(180 / segments * i) intersection() {
+			square(size + w);
+			rotate(-90 + 180 / segments) square(size + w);
+		}
+	}
+	
+	translate([0, -2 - separate, 0]) difference() {
+		translate([-size / 2 - w * 2, -w, 0]) square([size + w * 4, w + 2]);
+		translate([-size / 2 - w * 1, 0, 0]) square([size + w * 2, w + 2]);
+	}
+}
\ No newline at end of file
diff --git a/Arches/castle.scad b/Arches/castle.scad
new file mode 100755
index 0000000..dcd21de
--- /dev/null
+++ b/Arches/castle.scad
@@ -0,0 +1,31 @@
+// file castle.scad
+// Creates a simple castle wall with towers and crenellation
+// (c) 2020 Rich Cameron
+// released under a Creative Commons CC-BY 4.0 International License
+
+wall = 100; //length of a castle wall, mm
+height = 40; //height of a castle wall, mm
+thick = 4; //thickness of the wall, mm
+
+
+for(side = [0:1:3]) {
+	rotate(90 * side) {
+		translate([-wall / 2, wall / 2, 0]) {
+			translate([0, -thick / 2, 0]) {
+				cube([wall, thick, height - thick]);
+				for(crenellation = [0:thick * 2:wall - thick]) {
+					translate([crenellation, 0, 0]) {
+						cube([thick, thick, height]);
+					} //end translate
+				} //end for
+			} //end translate
+
+			cylinder(h = height, r = 1.5 * thick);
+			translate([0, 0, height]) {
+				cylinder(h = 3 * thick, r1 = 1.5 * thick, r2 = 0);
+			} //end translate
+		} //end translate
+	} //end rotate
+} //end for
+
+
diff --git a/Arches/castle_advanced.scad b/Arches/castle_advanced.scad
new file mode 100755
index 0000000..4c8f066
--- /dev/null
+++ b/Arches/castle_advanced.scad
@@ -0,0 +1,53 @@
+// file castle_advanced.scad
+// Creates a castle with Gothic or circular arched windows
+// (c) 2020 Rich Cameron
+// released under a Creative Commons CC-BY 4.0 International License
+
+wall = 100; //length of a castle wall, mm
+height = 40; //height of a castle wall, mm
+thick = 4; //thickness of the wall, mm
+
+$fs = .2;
+$fa = 2;
+//make the basic castle and then subtract off the windows/door
+difference() {
+	for(side = [0:1:3]) {
+		rotate(90 * side) {
+			translate([-wall / 2, wall / 2, 0]) {
+				translate([0, -thick / 2, 0]) {
+					cube([wall, thick, height]);
+					for(crenellation = [0:thick * 2:wall - thick]) {
+						translate([crenellation, 0, 0]) {
+							cube([thick, thick, height + thick]);
+						} //end translate
+					} //end for
+				} //end translate
+					
+				cylinder(h = height + thick, r = 1.5 * thick);
+				translate([0, 0, height + thick]) {
+					cylinder(h = 3 * thick, r1 = 1.5 * thick, r2 = 0);
+				} //end translate
+			} //end translate
+		} //end rotate
+	} //end for
+	for(a = [1:1:3]) rotate([90, 0, a * 90]) for(i = [-2:1:2]) translate([i * wall / 6, 20, 0]) arch([5, 10, wall], true);
+	rotate([90, 0, 0]) {
+		for(i = [-2, 2]) translate([i * wall / 6, 20, 0]) arch([5, 10, wall], true);
+		translate([0, 20, 0]) arch([25, 25, wall], false);
+	}
+}
+//module which creates arched door on one side and windows on all
+
+module arch(size, gothic = true) {
+	if(size[2]) {
+		linear_extrude(size[2]) arch([size[0], size[1], 0], gothic);
+	}
+	else intersection() {
+		union() {
+			if(gothic) intersection_for(i = [-1, 1]) translate([size[0] / 2 * i, 0, 0]) circle(size[0]);
+			else circle(size[0] / 2);
+			if(height > 0) translate([-size[0] / 2, -size[1], 0]) square([size[0], size[1]]);
+		}
+		translate([-size[0] / 2, -size[1], 0]) square([size[0], size[0] + size[1]]);
+	}
+}
\ No newline at end of file
diff --git a/Arches/tracery.scad b/Arches/tracery.scad
new file mode 100755
index 0000000..843164e
--- /dev/null
+++ b/Arches/tracery.scad
@@ -0,0 +1,31 @@
+// file tracery.scad
+// Creates a Gothic window with tracery
+// (c) 2020 Rich Cameron
+// released under a Creative Commons CC-BY 4.0 International License
+
+size = 60; //Overall height of the piece, mm 
+wall = 1; //Thickness of the walls, mm
+depth = 5; //Depth of the tracery walls, mm
+backing = .5; //Thickness of a solid backing plate; 0 creates open tracery
+
+$fs = .2;
+$fa = 2;
+
+module shape() {
+	translate([0, -size / 2, 0]) square(size, center = true);
+	intersection_for(i = [1, -1]) translate([i * size / 2, 0, 0]) circle(size);
+}
+
+if(backing) #linear_extrude(backing) shape();
+
+for(i = [0:4]) linear_extrude(backing + depth / (i + 1)) for(j = [0:pow(2, i) - 1]) translate([-size * (-.5 + pow(2, -i - 1) + j / pow(2, i)), 0, 0]) difference() {
+	offset(wall / 2) intersection_for(k = [-1, 1]) translate([k * size * (.5 - 1 / pow(2, i + 1)), 0, 0]) shape();
+	offset(-wall / 2) intersection_for(k = [-1, 1]) translate([k * size * (.5 - 1 / pow(2, i + 1)), 0, 0]) shape();
+}
+
+linear_extrude(backing + depth / 4) translate([0, size * .6, 0]) rotate(180) difference() {
+	offset(wall / 2) trefoil(size * .1125);
+	offset(-wall / 2) trefoil(size * .1125);
+}
+
+module trefoil(r) for(a = [0:120:359]) rotate(a) translate([0, r, 0]) circle(r);
\ No newline at end of file
diff --git a/gnomon.scad b/Gnomon/gnomon.scad
similarity index 100%
rename from gnomon.scad
rename to Gnomon/gnomon.scad
diff --git a/Gnomon/sun_dial_gnomon.scad b/Gnomon/sun_dial_gnomon.scad
new file mode 100755
index 0000000..ac4c110
--- /dev/null
+++ b/Gnomon/sun_dial_gnomon.scad
@@ -0,0 +1,13 @@
+// file sun_dial_gnomon.scad
+// Creates a gnomon for a sundial to be used at the given latitude
+// 
+// (c) 2020 Rich Cameron
+// released under a Creative Commons CC-BY 4.0 International License
+
+length = 100; //length of the base of the triangle, mm 
+base = 30; //width of the base of the triangle, mm
+latitude = 34.1; //latitude of user, degrees 
+thickness = 2.2; //thickness of the piece, mm
+
+rotate([90, 0, 90]) linear_extrude(thickness, center = true) polygon([[0, 0], [0, length], [length * tan(abs(latitude)), 0]]);
+translate([-base / 2, -thickness, 0]) cube([base, thickness, length]);
diff --git a/Polygons+Polyhedrons/edge_platonic_solids.scad b/Polygons+Polyhedrons/edge_platonic_solids.scad
new file mode 100755
index 0000000..5491372
--- /dev/null
+++ b/Polygons+Polyhedrons/edge_platonic_solids.scad
@@ -0,0 +1,27 @@
+// file edge_platonic_solids.scad
+// creates platonic solids specified by length of an edge in mm
+// (c) 2020 Rich Cameron
+// released under a Creative Commons CC-BY 4.0 International License
+
+edge = 50 / sqrt(2); //length of the edge of each solid
+// to get just one solid, comment out the others
+
+%rotate([45, 35, 0]) cube(48.8, center = true);
+
+//translate(edge * [.75, -.75, 0]) tetrahedron(edge);
+//translate(edge * [1.5, 1.5, 0]) cube(edge);
+octahedron(edge, true);
+//translate(edge * [2, 0, 0]) dodecahedron(edge);
+//translate(edge * [.5, 1.6, 0]) icosahedron(edge);
+
+//%cube(1, center = true);
+
+phi = (1 + sqrt(5)) / 2;
+
+module tetrahedron(edge = 1, center = false) translate([0, 0, center ? 0 : edge * sqrt(2) / sqrt(3) / 2]) cylinder(r1 = edge / sqrt(3), r2 = 0, h = edge * sqrt(2) / sqrt(3), center = true, $fn = 3);
+
+module octahedron(edge = 1, center = false) translate([0, 0, center ? 0 : edge * sqrt(2) / sqrt(3) / 2]) hull() for(i = [0, 1]) mirror([0, 0, i]) mirror([i, 0, 0]) tetrahedron(edge, true);
+	
+module dodecahedron(edge = 1, center = false) scale(pow(phi, 5 / 2) / pow(5, 1 / 4)) translate([0, 0, center ? 0 : edge / 2]) intersection_for(a = [0:72:360]) rotate([0, a ? atan(2) : 0, a]) cylinder(r = edge, h = edge, center = true, $fn = 10);
+
+module icosahedron(edge = 1, center = false) scale(pow(phi, 2) / sqrt(3)) translate([0, 0, center ? 0 : edge / 2]) intersection_for(a = [0:120:360], b = [-60, 0, 60]) rotate([0, a ? acos(sqrt(5) / 3) : 0, a]) rotate([0, b ? acos(sqrt(5) / 3) : 0, a ? b : 0]) cylinder(r = edge, h = edge, $fn = 6, center = true);
\ No newline at end of file
diff --git a/Reuleaux/meissner.scad b/Reuleaux/meissner.scad
new file mode 100755
index 0000000..ba84caf
--- /dev/null
+++ b/Reuleaux/meissner.scad
@@ -0,0 +1,23 @@
+// file meissner.scad
+// Creates miessner tetrahedrons 
+// 
+// (c) 2020 Rich Cameron
+// released under a Creative Commons CC-BY 4.0 International License
+
+size = 50; // radius of the spheres, and also the constant width 
+meissner = 1; // Meissner tetrahedron (1 or 2) or 0 for Reuleaux tetrahedron 
+
+$fs = .2;
+$fa = 2;
+
+difference() {
+	intersection_for(i = [0:3]) translate(size / sqrt(2) / 2 * [(i % 2) ? 1 : -1, (i == 1 || i == 2) ? -1 : 1, (i > 1) ? 1 : -1]) sphere(size);
+	if(meissner) for(i = [0:2]) rotate(90 * [i ? 1 : 0, (i == 2) ? 1 : 0, i]) rotate([0, (meissner - 1) * 180, 0]) translate(size * 3/4 * sqrt(2) * [0, 0, 1]) rotate([90, 0, -45]) 
+		difference() {
+		scale([1 / sqrt(2), 1, 1]) rotate(45) cube(size, center = true);
+		translate(size / sqrt(2) * [0, -1, 0]) rotate_extrude() intersection() {
+			translate(size * [-cos(30), 0, 0]) circle(size);
+			translate([0, -size / 2, 0]) square(size);
+		}
+	}
+}
\ No newline at end of file
diff --git a/Reuleaux/revolved_reuleaux.scad b/Reuleaux/revolved_reuleaux.scad
new file mode 100755
index 0000000..2a99279
--- /dev/null
+++ b/Reuleaux/revolved_reuleaux.scad
@@ -0,0 +1,20 @@
+// file revolved_reuleaux.scad
+// Creates Reuleaux constant-width figures of revolultion
+// 
+// (c) 2020 Rich Cameron
+// released under a Creative Commons CC-BY 4.0 International License
+
+width = 50; //constant width 
+reuleaux = 3; // number of sides, odd numbers 3 thru 13
+
+$fs = .2;
+$fa = 2;
+
+if((reuleaux % 2) != 1 || reuleaux < 3) {
+	echo("Reuleaux polygons must have an odd number of sides.");
+} else {
+	rotate_extrude() intersection() {
+		intersection_for(a = [0:360 / reuleaux:359]) rotate(a) translate([0, width / (sin(180 / reuleaux) / sin(90 / reuleaux)), 0]) circle(width);
+		translate([0, -width, 0]) square(width * 2);
+	}
+}
\ No newline at end of file
diff --git a/Slices+Sections/centerfinders.scad b/Slices+Sections/centerfinders.scad
new file mode 100755
index 0000000..a9b20f7
--- /dev/null
+++ b/Slices+Sections/centerfinders.scad
@@ -0,0 +1,43 @@
+// file centerfinders.scad
+// Creates nested "D" shapes to construct parabolas and hyperbolas
+// (c) 2020 Rich Cameron
+// released under a Creative Commons CC-BY 4.0 International License
+
+
+w = 2; //width of the D lines, mm
+h = 2; //thickness of the D lines, mm
+hole = 1; //size of notch to mark parabola, mm
+enclosed = false; //if true makes a circle around the marking hole
+
+radii = [10:6:60]; //radii of the "D" shapes
+
+$fs = .2;
+$fa = 2;
+
+echo(len([for(i = radii) i]) - 1);
+
+for(i = [0:len([for(i = radii) i]) - 1], radius = [for(i = radii) i][i]) translate([0, -i * (enclosed ? 2 : 1) * (w + hole / 2 + .5), 0]) difference() {
+	if(h) {
+		linear_extrude(h, convexity = 2) shape(radius, hole, w, enclosed);
+		if(enclosed) cylinder(r1 = 0, r2 = h * 2, h = h * 2);
+	} else shape(radius, hole, w, enclosed);
+}
+
+module shape(radius, hole, w, enclosed = false) difference() {
+			intersection() {
+				circle(radius);
+				translate([-radius, enclosed ? -w / 2 : 0, 0]) square(radius * 2);
+			}
+			circle(hole / 2);
+			offset(-w) difference() {
+				intersection() {
+					circle(radius);
+					translate([-radius, enclosed ? -w / 2 : 0, 0]) square(radius * 2);
+				}
+				circle(hole / 2);
+			}
+		}
+		if(enclosed) difference() {
+			offset(w) circle(hole / 2);
+			circle(hole / 2);
+		}
\ No newline at end of file
diff --git a/ellipse.scad b/Slices+Sections/ellipse.scad
similarity index 100%
rename from ellipse.scad
rename to Slices+Sections/ellipse.scad
diff --git a/sphere_cone_volume.scad b/Slices+Sections/sphere_cone_volume.scad
similarity index 100%
rename from sphere_cone_volume.scad
rename to Slices+Sections/sphere_cone_volume.scad
diff --git a/Triangles/theodorus.scad b/Triangles/theodorus.scad
old mode 100644
new mode 100755
index 79ebe89..4c117bf
--- a/Triangles/theodorus.scad
+++ b/Triangles/theodorus.scad
@@ -2,8 +2,10 @@
 // makes a spiral of theodorus
 // (c) 2020, Rich Cameron, licensed Creative Commons CC-BY4.0
 
-max = 53; // number of triangles to be made
-// the last triangle's sides will be sqrt(max), 1 and sqrt(max + 1)
+max = 53; // number of triangles to be made -1 
+// if max = 16, 17 triangles will be made
+// triangles are right triangles with sides  1 : sqrt(n-1) :sqrt(n)
+// 1 <= n <= max +1
 
 xyscale = 10;
 wall = 1;
diff --git a/golden_ratio.scad b/golden_ratio.scad
new file mode 100755
index 0000000..08a8f12
--- /dev/null
+++ b/golden_ratio.scad
@@ -0,0 +1,8 @@
+// file golden_ratio.scad
+// Creates successive rectangles whose smallest side is the large side of 
+// the next rectangle. Rectangle sides in ratio of phi to each other
+// (c) 2020 Rich Cameron
+// released under a Creative Commons CC-BY 4.0 International License
+phi = (1 + sqrt(5)) / 2;
+
+for(i = [0:10]) rotate(i * 0) mirror((i % 2) * [1, -1, 0]) linear_extrude(12 - i) square(pow(phi, i) * [1, phi]);
\ No newline at end of file
diff --git a/theodorus.scad b/theodorus.scad
deleted file mode 100755
index 4c117bf..0000000
--- a/theodorus.scad
+++ /dev/null
@@ -1,31 +0,0 @@
-// theodorus.scad
-// makes a spiral of theodorus
-// (c) 2020, Rich Cameron, licensed Creative Commons CC-BY4.0
-
-max = 53; // number of triangles to be made -1 
-// if max = 16, 17 triangles will be made
-// triangles are right triangles with sides  1 : sqrt(n-1) :sqrt(n)
-// 1 <= n <= max +1
-
-xyscale = 10;
-wall = 1;
-base = 1;
-
-zstep = .2; //should be a multiple of layer height
-
-$fs = .2;
-$fa = 2;
-
-
-function angle(n) = (n > 1) ? asin(1 / sqrt(n)) + angle(n - 1) : 0;
-
-for(i = [1:max]) rotate(angle(i)) linear_extrude(base + (max + 1 - i) * zstep) difference() {
-	offset(wall / 2) polygon(xyscale * [[0, 0], [sqrt(i), 0], [sqrt(i), 1]]);
-	offset(-wall / 2) polygon(xyscale * [[0, 0], [sqrt(i), 0], [sqrt(i), 1]]);
-}
-
-for(i = [1:max]) rotate(angle(i)) linear_extrude(base) difference() {
-	polygon(xyscale * [[0, 0], [sqrt(i), 0], [sqrt(i), 1]]);
-}
-
-echo(angle(max + 1) % 360);
\ No newline at end of file
diff --git a/tracery.scad b/tracery.scad
deleted file mode 100644
index 2160eec..0000000
--- a/tracery.scad
+++ /dev/null
@@ -1,24 +0,0 @@
-size = 60;
-wall = 1;
-
-
-$fs = .2;
-$fa = 2;
-
-
-
-module shape() {
-	translate([0, -size / 2, 0]) square(size, center = true);
-	intersection_for(i = [1, -1]) translate([i * size / 2, 0, 0]) circle(size);
-}
-
-#linear_extrude(.5) shape();
-
-for(i = [0:4]) linear_extrude(.5 + 10 / (i + 1)) for(j = [0:pow(2, i) - 1]) translate([-size * (-.5 + pow(2, -i - 1) + j / pow(2, i)), 0, 0]) difference() {
-	offset(wall / 2) intersection_for(k = [-1, 1]) translate([k * size * (.5 - 1 / pow(2, i + 1)), 0, 0]) shape();
-	offset(-wall / 2) intersection_for(k = [-1, 1]) translate([k * size * (.5 - 1 / pow(2, i + 1)), 0, 0]) shape();
-}
-
-
-
-