diff --git a/README.rst b/README.rst
index 592287c..6e357b1 100644
--- a/README.rst
+++ b/README.rst
@@ -1,3 +1,7 @@
+.. image:: docs/nutNbolt.png
+        :width: 20%
+        :alt: bolt-in-nut logo
+
 threadlib
 +++++++++++++++++++++++++++
 
@@ -27,11 +31,15 @@ inside the ranges allowed by the norms.
 Usage
 ===========================
 
-To create a bolt (without head) with 10 turns of M12 thread:
+To create a bolt (without head) with 5 turns of M4 thread:
 
 .. code-block:: OpenSCAD
 
-        bolt("M12x0.5", turns=10);
+        bolt("M4", turns=5);
+
+.. image:: docs/bolt-M4.png
+        :width: 30%
+        :alt: Bolt with M4 thread
 
 A nut:
 
@@ -39,8 +47,12 @@ A nut:
 
         nut("M12x0.5", turns=10, Douter=40);
 
+.. image:: docs/nut-M12x0.5.png
+        :width: 30%
+        :alt: M12x0.5 nut
+
 Note that for a nut you also have to specify an outer diameter. The inner
-diameter is implicitly given by the thread designator ("G1" in this case).
+diameter is implicitly given by the thread designator ("M12x0.5" in this case).
 
 If you only need the threads alone:
 
diff --git a/autogenerate.awk b/design/autogenerate.awk
similarity index 100%
rename from autogenerate.awk
rename to design/autogenerate.awk
diff --git a/threads.xlsx b/design/threads.xlsx
similarity index 100%
rename from threads.xlsx
rename to design/threads.xlsx
diff --git a/docs/Makefile b/docs/Makefile
new file mode 100644
index 0000000..57bb209
--- /dev/null
+++ b/docs/Makefile
@@ -0,0 +1,19 @@
+os = /usr/local/bin/openscad
+opts =
+imgs = bolt-M4.png nut-M12x0.5.png nutNbolt.png
+
+.PHONY: all
+all: $(imgs)
+
+bolt-M4.png: bolt.scad
+	$(os) $(opts) --D 'type="M4"' --camera=0.49,-0.26,1.55,74.6,0.0,78.9,20 --imgsize=2048,2048 -o $@ $<
+
+nut-M12x0.5.png: nut.scad
+	$(os) $(opts) --D 'type="M12x0.5"' --D 'turns=10' --D 'Douter=16' --camera=-2.2,1.2,1.8,66,0,73,52 --imgsize=2048,2048 --projection=ortho -o $@ $<
+
+nutNbolt.png: nutNbolt.scad
+	$(os) $(opts) --camera=-0.24,1.19,4.24,83,0,326.9,40.3 --imgsize=2048,2048 --projection=ortho -o $@ $<
+
+.PHONY: clean
+clean:
+	rm *.png
diff --git a/docs/bolt.scad b/docs/bolt.scad
new file mode 100644
index 0000000..18d0a58
--- /dev/null
+++ b/docs/bolt.scad
@@ -0,0 +1,15 @@
+/*
+Create nice previews for documentation
+
+:Author: Adrian Schlatter
+:Date: 2019-04-10
+:License: 3-Clause BSD. See LICENSE.
+*/
+
+use <threadlib/threadlib.scad>
+
+type = "M6";
+turns = 5;
+higbee_arc = 45;
+
+bolt(type, turns, higbee_arc=higbee_arc);
diff --git a/docs/nut.scad b/docs/nut.scad
new file mode 100644
index 0000000..253a40d
--- /dev/null
+++ b/docs/nut.scad
@@ -0,0 +1,16 @@
+/*
+Create nice previews for documentation
+
+:Author: Adrian Schlatter
+:Date: 2019-04-10
+:License: 3-Clause BSD. See LICENSE.
+*/
+
+use <threadlib/threadlib.scad>
+
+type = "M12x0.5";
+turns = 10;
+Douter = 16;
+higbee_arc = 45;
+
+nut(type, turns, Douter, higbee_arc=higbee_arc);
diff --git a/docs/nutNbolt.scad b/docs/nutNbolt.scad
new file mode 100644
index 0000000..317aaf6
--- /dev/null
+++ b/docs/nutNbolt.scad
@@ -0,0 +1,26 @@
+/*
+Create nice previews for documentation
+
+:Author: Adrian Schlatter
+:Date: 2019-04-10
+:License: 3-Clause BSD. See LICENSE.
+*/
+
+use <threadlib/threadlib.scad>
+
+type = "M6";
+turns = 6;
+higbee_arc = 45;
+
+P = thread_specs(str(type, "-ext"))[0];
+dz = (turns / 2 - 1/4) * P;
+Douter = thread_specs(str(type, "-int"))[2] * 1.5;
+
+translate([0, 0, dz])
+    rotate([0, 0, -90])
+        bolt(type, turns, higbee_arc=higbee_arc);
+intersection() {
+    nut(type, turns, Douter, higbee_arc=higbee_arc);
+    translate([-100, 0, 0])
+        cube([200, 200, 200]);
+};
\ No newline at end of file
diff --git a/test.scad b/tests/test.scad
similarity index 100%
rename from test.scad
rename to tests/test.scad