diff --git a/pills.scad b/pills.scad
index 3422df4..bce1f87 100644
--- a/pills.scad
+++ b/pills.scad
@@ -1,4 +1,4 @@
-use <threads.scad>;
+use <threads_v2.scad>;
 $fa = 1;
 $fs = 0.4;
 
@@ -7,6 +7,7 @@ height_total = 35;
 thickness = 2;
 
 cap_height = 10;
+corner_radius = 2;
 
 inner_radius = outer_radius - thickness;
 height_base = height_total - cap_height;
@@ -14,9 +15,11 @@ height_thread = cap_height - thickness;
 
 thread_radius = inner_radius + (thickness / 2);
 
+
 // base shape
 difference() {
-  cylinder(h=height_base, r=outer_radius);
+  //cylinder(h=height_base, r=outer_radius);
+  rounded_cylinder(outer_radius, height_base, corner_radius);
   translate([0, 0, thickness])
     cylinder(h=height_base, r = inner_radius);
 }
@@ -36,13 +39,26 @@ translate([0, 0, height_base - 1]) {
       ScrewThread( thread_radius*2, height_thread + 1, pitch=4);
       cylinder(h = 1, r=outer_radius);
     }
-translate([0, 0, -0.01])
-    cylinder(h=height_thread+2, r=thread_radius - thickness*2);
+    translate([0, 0, -0.01])
+      cylinder(h=height_thread+2, r=thread_radius - thickness*2);
   }
 }
 
 // cap
-translate([70, 0, cap_height]) rotate([180, 0,0]) {
+translate([70, 0, cap_height])  rotate([180, 0,0]) {
   ScrewHole(thread_radius * 2, cap_height - thickness, pitch=4)
-    cylinder(h=cap_height, r=outer_radius);
+    rotate([180, 0, 0]) translate([0, 0, -cap_height]) rounded_cylinder(outer_radius, cap_height, corner_radius);
+}
+
+// test rounded edges
+//translate([-70, 0, 0]){
+//  rounded_cylinder(30, height_base, 5);
+//}
+module rounded_cylinder(r,h,c) {
+  rotate_extrude(convexity = 10)
+    hull() {
+      translate([r-c,c,0]) circle(c);
+      translate([0,0,0]) square([r-2*c, 2*c]);
+      translate([0,2*c,0]) square([r, h-2*c]);
+    }
 }
diff --git a/threads_v2.scad b/threads_v2.scad
new file mode 100644
index 0000000..44057c5
--- /dev/null
+++ b/threads_v2.scad
@@ -0,0 +1,630 @@
+// Created 2016-2017 by Ryan A. Colyer.
+// This work is released with CC0 into the public domain.
+// https://creativecommons.org/publicdomain/zero/1.0/
+//
+// http://www.thingiverse.com/thing:1686322
+
+
+screw_resolution = 0.2;  // in mm
+
+
+// Provides standard metric thread pitches.
+function ThreadPitch(diameter) =
+  (diameter <= 64) ?
+    lookup(diameter, [
+      [2, 0.4],
+      [2.5, 0.45],
+      [3, 0.5],
+      [4, 0.7],
+      [5, 0.8],
+      [6, 1.0],
+      [7, 1.0],
+      [8, 1.25],
+      [10, 1.5],
+      [12, 1.75],
+      [14, 2.0],
+      [16, 2.0],
+      [18, 2.5],
+      [20, 2.5],
+      [22, 2.5],
+      [24, 3.0],
+      [27, 3.0],
+      [30, 3.5],
+      [33, 3.5],
+      [36, 4.0],
+      [39, 4.0],
+      [42, 4.5],
+      [48, 5.0],
+      [52, 5.0],
+      [56, 5.5],
+      [60, 5.5],
+      [64, 6.0]
+    ]) :
+    diameter * 6.0 / 64;
+
+
+// Provides standard metric hex head widths across the flats.
+function HexAcrossFlats(diameter) =
+  (diameter <= 64) ?
+    lookup(diameter, [
+      [2, 4],
+      [2.5, 5],
+      [3, 5.5],
+      [3.5, 6],
+      [4, 7],
+      [5, 8],
+      [6, 10],
+      [7, 11],
+      [8, 13],
+      [10, 16],
+      [12, 18],
+      [14, 21],
+      [16, 24],
+      [18, 27],
+      [20, 30],
+      [22, 34],
+      [24, 36],
+      [27, 41],
+      [30, 46],
+      [33, 50],
+      [36, 55],
+      [39, 60],
+      [42, 65],
+      [48, 75],
+      [52, 80],
+      [56, 85],
+      [60, 90],
+      [64, 95]
+    ]) :
+    diameter * 95 / 64;
+
+// Provides standard metric hex head widths across the corners.
+function HexAcrossCorners(diameter) =
+  HexAcrossFlats(diameter) / cos(30);
+
+
+// Provides standard metric hex (Allen) drive widths across the flats.
+function HexDriveAcrossFlats(diameter) =
+  (diameter <= 64) ?
+    lookup(diameter, [
+      [2, 1.5],
+      [2.5, 2],
+      [3, 2.5],
+      [3.5, 3],
+      [4, 3],
+      [5, 4],
+      [6, 5],
+      [7, 5],
+      [8, 6],
+      [10, 8],
+      [12, 10],
+      [14, 12],
+      [16, 14],
+      [18, 15],
+      [20, 17],
+      [22, 18],
+      [24, 19],
+      [27, 20],
+      [30, 22],
+      [33, 24],
+      [36, 27],
+      [39, 30],
+      [42, 32],
+      [48, 36],
+      [52, 36],
+      [56, 41],
+      [60, 42],
+      [64, 46]
+    ]) :
+    diameter * 46 / 64;
+
+// Provides standard metric hex (Allen) drive widths across the corners.
+function HexDriveAcrossCorners(diameter) =
+  HexDriveAcrossFlats(diameter) / cos(30);
+
+// Provides metric countersunk hex (Allen) drive widths across the flats.
+function CountersunkDriveAcrossFlats(diameter) =
+  (diameter <= 14) ?
+    HexDriveAcrossFlats(HexDriveAcrossFlats(diameter)) :
+    round(0.6*diameter);
+
+// Provides metric countersunk hex (Allen) drive widths across the corners.
+function CountersunkDriveAcrossCorners(diameter) =
+  CountersunkDriveAcrossFlats(diameter) / cos(30);
+
+// Provides standard metric nut thickness.
+function NutThickness(diameter) =
+  (diameter <= 64) ?
+    lookup(diameter, [
+      [2, 1.6],
+      [2.5, 2],
+      [3, 2.4],
+      [3.5, 2.8],
+      [4, 3.2],
+      [5, 4.7],
+      [6, 5.2],
+      [7, 6.0],
+      [8, 6.8],
+      [10, 8.4],
+      [12, 10.8],
+      [14, 12.8],
+      [16, 14.8],
+      [18, 15.8],
+      [20, 18.0],
+      [22, 21.1],
+      [24, 21.5],
+      [27, 23.8],
+      [30, 25.6],
+      [33, 28.7],
+      [36, 31.0],
+      [42, 34],
+      [48, 38],
+      [56, 45],
+      [64, 51]
+    ]) :
+    diameter * 51 / 64;
+  
+
+// This generates a closed polyhedron from an array of arrays of points,
+// with each inner array tracing out one loop outlining the polyhedron.
+// pointarrays should contain an array of N arrays each of size P outlining a
+// closed manifold.  The points must obey the right-hand rule.  For example,
+// looking down, the P points in the inner arrays are counter-clockwise in a
+// loop, while the N point arrays increase in height.  Points in each inner
+// array do not need to be equal height, but they usually should not meet or
+// cross the line segments from the adjacent points in the other arrays.
+// (N>=2, P>=3)
+// Core triangles:
+//   [j][i], [j+1][i], [j+1][(i+1)%P]
+//   [j][i], [j+1][(i+1)%P], [j][(i+1)%P]
+//   Then triangles are formed in a loop with the middle point of the first
+//   and last array.
+module ClosePoints(pointarrays) {
+  function recurse_avg(arr, n=0, p=[0,0,0]) = (n>=len(arr)) ? p :
+    recurse_avg(arr, n+1, p+(arr[n]-p)/(n+1));
+
+  N = len(pointarrays);
+  P = len(pointarrays[0]);
+  NP = N*P;
+  lastarr = pointarrays[N-1];
+  midbot = recurse_avg(pointarrays[0]);
+  midtop = recurse_avg(pointarrays[N-1]);
+
+  faces_bot = [
+    for (i=[0:P-1])
+      [0,i+1,1+(i+1)%len(pointarrays[0])]
+  ];
+
+  loop_offset = 1;
+  bot_len = loop_offset + P;
+
+  faces_loop = [
+    for (j=[0:N-2], i=[0:P-1], t=[0:1])
+      [loop_offset, loop_offset, loop_offset] + (t==0 ?
+      [j*P+i, (j+1)*P+i, (j+1)*P+(i+1)%P] :
+      [j*P+i, (j+1)*P+(i+1)%P, j*P+(i+1)%P])
+  ];
+
+  top_offset = loop_offset + NP - P;
+  midtop_offset = top_offset + P;
+
+  faces_top = [
+    for (i=[0:P-1])
+      [midtop_offset,top_offset+(i+1)%P,top_offset+i]
+  ];
+
+  points = [
+    for (i=[-1:NP])
+      (i<0) ? midbot :
+      ((i==NP) ? midtop :
+      pointarrays[floor(i/P)][i%P])
+  ];
+  faces = concat(faces_bot, faces_loop, faces_top);
+
+  polyhedron(points=points, faces=faces);
+}
+
+
+
+// This creates a vertical rod at the origin with external threads.  It uses
+// metric standards by default.
+module ScrewThread(outer_diam, height, pitch=0, tooth_angle=30, tolerance=0.4, tip_height=0, tooth_height=0, tip_min_fract=0) {
+
+  pitch = (pitch==0) ? ThreadPitch(outer_diam) : pitch;
+  tooth_height = (tooth_height==0) ? pitch : tooth_height;
+  tip_min_fract = (tip_min_fract<0) ? 0 :
+    ((tip_min_fract>0.9999) ? 0.9999 : tip_min_fract);
+
+  outer_diam_cor = outer_diam + 0.25*tolerance; // Plastic shrinkage correction
+  inner_diam = outer_diam - pitch/tan(tooth_angle);
+  or = (outer_diam_cor < screw_resolution) ?
+    screw_resolution/2 : outer_diam_cor / 2;
+  ir = (inner_diam < screw_resolution) ? screw_resolution/2 : inner_diam / 2;
+  height = (height < screw_resolution) ? screw_resolution : height;
+
+  steps_per_loop_try = ceil(2*3.14159265359*or / screw_resolution);
+  steps_per_loop = (steps_per_loop_try < 4) ? 4 : steps_per_loop_try;
+  hs_ext = 3;
+  hsteps = ceil(3 * height / pitch) + 2*hs_ext;
+
+  extent = or - ir;
+
+  tip_start = height-tip_height;
+  tip_height_sc = tip_height / (1-tip_min_fract);
+
+  tip_height_ir = (tip_height_sc > tooth_height/2) ?
+    tip_height_sc - tooth_height/2 : tip_height_sc;
+
+  tip_height_w = (tip_height_sc > tooth_height) ? tooth_height : tip_height_sc;
+  tip_wstart = height + tip_height_sc - tip_height - tip_height_w;
+
+
+  function tooth_width(a, h, pitch, tooth_height, extent) =
+    let(
+      ang_full = h*360.0/pitch-a,
+      ang_pn = atan2(sin(ang_full), cos(ang_full)),
+      ang = ang_pn < 0 ? ang_pn+360 : ang_pn,
+      frac = ang/360,
+      tfrac_half = tooth_height / (2*pitch),
+      tfrac_cut = 2*tfrac_half
+    )
+    (frac > tfrac_cut) ? 0 : (
+      (frac <= tfrac_half) ?
+        ((frac / tfrac_half) * extent) :
+        ((1 - (frac - tfrac_half)/tfrac_half) * extent)
+    );
+
+
+  pointarrays = [
+    for (hs=[0:hsteps])
+      [
+        for (s=[0:steps_per_loop-1])
+          let(
+            ang_full = s*360.0/steps_per_loop,
+            ang_pn = atan2(sin(ang_full), cos(ang_full)),
+            ang = ang_pn < 0 ? ang_pn+360 : ang_pn,
+
+            h_fudge = pitch*0.001,
+
+            h_mod =
+              (hs%3 == 2) ?
+                ((s == steps_per_loop-1) ? tooth_height - h_fudge : (
+                 (s == steps_per_loop-2) ? tooth_height/2 : 0)) : (
+              (hs%3 == 0) ?
+                ((s == steps_per_loop-1) ? pitch-tooth_height/2 : (
+                 (s == steps_per_loop-2) ? pitch-tooth_height + h_fudge : 0)) :
+                ((s == steps_per_loop-1) ? pitch-tooth_height/2 + h_fudge : (
+                 (s == steps_per_loop-2) ? tooth_height/2 : 0))
+              ),
+
+            h_level =
+              (hs%3 == 2) ? tooth_height - h_fudge : (
+              (hs%3 == 0) ? 0 : tooth_height/2),
+
+            h_ub = floor((hs-hs_ext)/3) * pitch
+              + h_level + ang*pitch/360.0 - h_mod,
+            h_max = height - (hsteps-hs) * h_fudge,
+            h_min = hs * h_fudge,
+            h = (h_ub < h_min) ? h_min : ((h_ub > h_max) ? h_max : h_ub),
+
+            ht = h - tip_start,
+            hf_ir = ht/tip_height_ir,
+            ht_w = h - tip_wstart,
+            hf_w_t = ht_w/tip_height_w,
+            hf_w = (hf_w_t < 0) ? 0 : ((hf_w_t > 1) ? 1 : hf_w_t),
+          
+            ext_tip = (h <= tip_wstart) ? extent : (1-hf_w) * extent,
+            wnormal = tooth_width(ang, h, pitch, tooth_height, ext_tip),
+            w = (h <= tip_wstart) ? wnormal :
+              (1-hf_w) * wnormal +
+              hf_w * (0.1*screw_resolution + (wnormal * wnormal * wnormal /
+                (ext_tip*ext_tip+0.1*screw_resolution))),
+            r = (ht <= 0) ? ir + w :
+              ( (ht < tip_height_ir ? ((2/(1+(hf_ir*hf_ir))-1) * ir) : 0) + w)
+          )
+          [r*cos(ang), r*sin(ang), h]
+      ]
+  ];
+
+
+  ClosePoints(pointarrays);
+}
+
+
+// This creates a vertical rod at the origin with external auger-style
+// threads.
+module AugerThread(outer_diam, inner_diam, height, pitch, tooth_angle=30, tolerance=0.4, tip_height=0, tip_min_fract=0) {
+  tooth_height = tan(tooth_angle)*(outer_diam-inner_diam)/2;
+	ScrewThread(outer_diam, height, pitch, tooth_angle, tolerance, tip_height,
+    tooth_height, tip_min_fract);
+}
+
+
+// This creates a threaded hole in its children using metric standards by
+// default.
+module ScrewHole(outer_diam, height, position=[0,0,0], rotation=[0,0,0], pitch=0, tooth_angle=30, tolerance=0.4, tooth_height=0) {
+  extra_height = 0.001 * height;
+
+  difference() {
+    children();
+    translate(position)
+      rotate(rotation)
+      translate([0, 0, -extra_height/2])
+      ScrewThread(1.01*outer_diam + 1.25*tolerance, height + extra_height,
+        pitch, tooth_angle, tolerance, tooth_height=tooth_height);
+  }
+}
+
+
+// This creates an auger-style threaded hole in its children.
+module AugerHole(outer_diam, inner_diam, height, pitch, position=[0,0,0], rotation=[0,0,0], tooth_angle=30, tolerance=0.4) {
+  tooth_height = tan(tooth_angle)*(outer_diam-inner_diam)/2;
+  ScrewHole(outer_diam, height, position, rotation, pitch, tooth_angle,
+    tolerance, tooth_height=tooth_height);
+}
+
+
+// This inserts a ClearanceHole in its children.
+// The rotation vector is applied first, then the position translation,
+// starting from a position upward from the z-axis at z=0.
+module ClearanceHole(diameter, height, position=[0,0,0], rotation=[0,0,0], tolerance=0.4) {
+  extra_height = 0.001 * height;
+
+  difference() {
+    children();
+    translate(position)
+      rotate(rotation)
+      translate([0, 0, -extra_height/2])
+      cylinder(h=height + extra_height, r=(diameter/2+tolerance));
+  }
+}
+
+
+// This inserts a ClearanceHole with a recessed bolt hole in its children.
+// The rotation vector is applied first, then the position translation,
+// starting from a position upward from the z-axis at z=0.  The default
+// recessed parameters fit a standard metric bolt.
+module RecessedClearanceHole(diameter, height, position=[0,0,0], rotation=[0,0,0], recessed_diam=-1, recessed_height=-1, tolerance=0.4) {
+  recessed_diam = (recessed_diam < 0) ?
+    HexAcrossCorners(diameter) : recessed_diam;
+  recessed_height = (recessed_height < 0) ? diameter : recessed_height;
+  extra_height = 0.001 * height;
+
+  difference() {
+    children();
+    translate(position)
+      rotate(rotation)
+      translate([0, 0, -extra_height/2])
+      cylinder(h=height + extra_height, r=(diameter/2+tolerance));
+    translate(position)
+      rotate(rotation)
+      translate([0, 0, -extra_height/2])
+      cylinder(h=recessed_height + extra_height/2,
+        r=(recessed_diam/2+tolerance));
+  }
+}
+
+
+// This inserts a countersunk ClearanceHole in its children.
+// The rotation vector is applied first, then the position translation,
+// starting from a position upward from the z-axis at z=0.
+// The countersunk side is on the bottom by default.
+module CountersunkClearanceHole(diameter, height, position=[0,0,0], rotation=[0,0,0], sinkdiam=0, sinkangle=45, tolerance=0.4) {
+  extra_height = 0.001 * height;
+  sinkdiam = (sinkdiam==0) ? 2*diameter : sinkdiam;
+  sinkheight = ((sinkdiam-diameter)/2)/tan(sinkangle);
+
+  difference() {
+    children();
+    translate(position)
+      rotate(rotation)
+      translate([0, 0, -extra_height/2])
+      union() {
+        cylinder(h=height + extra_height, r=(diameter/2+tolerance));
+        cylinder(h=sinkheight + extra_height, r1=(sinkdiam/2+tolerance), r2=(diameter/2+tolerance), $fn=24*diameter);
+      }
+  }
+}
+
+
+// This inserts a Phillips tip shaped hole into its children.
+// The rotation vector is applied first, then the position translation,
+// starting from a position upward from the z-axis at z=0.
+module PhillipsTip(width=7, thickness=0, straightdepth=0, position=[0,0,0], rotation=[0,0,0]) {
+  thickness = (thickness <= 0) ? width*2.5/7 : thickness;
+  straightdepth = (straightdepth <= 0) ? width*3.5/7 : straightdepth;
+  angledepth = (width-thickness)/2;
+  height = straightdepth + angledepth;
+  extra_height = 0.001 * height;
+
+	difference() {
+		children();
+		translate(position)
+			rotate(rotation)
+			union() {
+				hull() {
+					translate([-width/2, -thickness/2, -extra_height/2])
+						cube([width, thickness, straightdepth+extra_height]);
+					translate([-thickness/2, -thickness/2, height-extra_height])
+						cube([thickness, thickness, extra_height]);
+				}
+				hull() {
+					translate([-thickness/2, -width/2, -extra_height/2])
+						cube([thickness, width, straightdepth+extra_height]);
+					translate([-thickness/2, -thickness/2, height-extra_height])
+						cube([thickness, thickness, extra_height]);
+				}
+			}
+  }
+}
+
+
+
+// Create a standard sized metric bolt with hex head and hex key.
+module MetricBolt(diameter, length, tolerance=0.4) {
+  drive_tolerance = pow(3*tolerance/HexDriveAcrossCorners(diameter),2)
+    + 0.75*tolerance;
+
+  difference() {
+    cylinder(h=diameter, r=(HexAcrossCorners(diameter)/2-0.5*tolerance), $fn=6);
+    cylinder(h=diameter,
+      r=(HexDriveAcrossCorners(diameter)+drive_tolerance)/2, $fn=6,
+      center=true);
+  }
+  translate([0,0,diameter-0.01])
+    ScrewThread(diameter, length+0.01, tolerance=tolerance,
+      tip_height=ThreadPitch(diameter), tip_min_fract=0.75);
+}
+
+
+// Create a standard sized metric countersunk (flat) bolt with hex key drive.
+// In compliance with convention, the length for this includes the head.
+module MetricCountersunkBolt(diameter, length, tolerance=0.4) {
+  drive_tolerance = pow(3*tolerance/CountersunkDriveAcrossCorners(diameter),2)
+    + 0.75*tolerance;
+
+  difference() {
+    cylinder(h=diameter/2, r1=diameter, r2=diameter/2, $fn=24*diameter);
+    cylinder(h=0.8*diameter,
+      r=(CountersunkDriveAcrossCorners(diameter)+drive_tolerance)/2, $fn=6,
+      center=true);
+  }
+  translate([0,0,diameter/2-0.01])
+    ScrewThread(diameter, length-diameter/2+0.01, tolerance=tolerance,
+      tip_height=ThreadPitch(diameter), tip_min_fract=0.75);
+}
+
+
+// Create a standard sized metric countersunk (flat) bolt with hex key drive.
+// In compliance with convention, the length for this includes the head.
+module MetricWoodScrew(diameter, length, tolerance=0.4) {
+  drive_tolerance = pow(3*tolerance/CountersunkDriveAcrossCorners(diameter),2)
+    + 0.75*tolerance;
+
+	PhillipsTip(diameter-2)
+    union() {
+      cylinder(h=diameter/2, r1=diameter, r2=diameter/2, $fn=24*diameter);
+
+      translate([0,0,diameter/2-0.01])
+        ScrewThread(diameter, length-diameter/2+0.01, tolerance=tolerance,
+	    		tip_height=diameter);
+    }
+}
+
+
+// Create a standard sized metric hex nut.
+module MetricNut(diameter, thickness=0, tolerance=0.4) {
+  thickness = (thickness==0) ? NutThickness(diameter) : thickness;
+  ScrewHole(diameter, thickness, tolerance=tolerance)
+    cylinder(h=thickness, r=HexAcrossCorners(diameter)/2-0.5*tolerance, $fn=6);
+}
+
+
+// Create a convenient washer size for a metric nominal thread diameter.
+module MetricWasher(diameter) {
+  difference() {
+    cylinder(h=diameter/5, r=1.15*diameter, $fn=24*diameter);
+    cylinder(h=2*diameter, r=0.575*diameter, $fn=12*diameter, center=true);
+  }
+}
+
+
+// Solid rod on the bottom, external threads on the top.
+module RodStart(diameter, height, thread_len=0, thread_diam=0, thread_pitch=0) {
+  // A reasonable default.
+  thread_diam = (thread_diam==0) ? 0.75*diameter : thread_diam;
+  thread_len = (thread_len==0) ? 0.5*diameter : thread_len;
+  thread_pitch = (thread_pitch==0) ? ThreadPitch(thread_diam) : thread_pitch;
+    
+  cylinder(r=diameter/2, h=height, $fn=24*diameter);
+
+  translate([0, 0, height])
+    ScrewThread(thread_diam, thread_len, thread_pitch,
+      tip_height=thread_pitch, tip_min_fract=0.75);
+}
+
+
+// Solid rod on the bottom, internal threads on the top.
+// Flips around x-axis after printing to pair with RodStart.
+module RodEnd(diameter, height, thread_len=0, thread_diam=0, thread_pitch=0) {
+  // A reasonable default.
+  thread_diam = (thread_diam==0) ? 0.75*diameter : thread_diam;
+  thread_len = (thread_len==0) ? 0.5*diameter : thread_len;
+  thread_pitch = (thread_pitch==0) ? ThreadPitch(thread_diam) : thread_pitch;
+
+  ScrewHole(thread_diam, thread_len, [0, 0, height], [180,0,0], thread_pitch)
+    cylinder(r=diameter/2, h=height, $fn=24*diameter);
+}
+
+
+// Internal threads on the bottom, external threads on the top.
+module RodExtender(diameter, height, thread_len=0, thread_diam=0, thread_pitch=0) {
+  // A reasonable default.
+  thread_diam = (thread_diam==0) ? 0.75*diameter : thread_diam;
+  thread_len = (thread_len==0) ? 0.5*diameter : thread_len;
+  thread_pitch = (thread_pitch==0) ? ThreadPitch(thread_diam) : thread_pitch;
+  
+  max_bridge = height - thread_len;
+  // Use 60 degree slope if it will fit.
+  bridge_height = ((thread_diam/4) < max_bridge) ? thread_diam/4 : max_bridge;
+
+  difference() {
+    union() {
+      ScrewHole(thread_diam, thread_len, pitch=thread_pitch)
+        cylinder(r=diameter/2, h=height, $fn=24*diameter);
+  
+      translate([0,0,height])
+        ScrewThread(thread_diam, thread_len, pitch=thread_pitch,
+          tip_height=thread_pitch, tip_min_fract=0.75);
+    }
+    // Carve out a small conical area as a bridge.
+    translate([0,0,thread_len])
+      cylinder(h=bridge_height, r1=thread_diam/2, r2=0.1);
+  }
+}
+
+
+// Produces a matching set of metric bolts, nuts, and washers.
+module MetricBoltSet(diameter, length, quantity=1) {
+  for (i=[0:quantity-1]) {
+    translate([0, i*4*diameter, 0]) MetricBolt(diameter, length);
+    translate([4*diameter, i*4*diameter, 0]) MetricNut(diameter);
+    translate([8*diameter, i*4*diameter, 0]) MetricWasher(diameter);
+  }
+}
+
+
+module Demo() {
+  translate([0,-0,0]) MetricBoltSet(3, 8);
+  translate([0,-20,0]) MetricBoltSet(4, 8);
+  translate([0,-40,0]) MetricBoltSet(5, 8);
+  translate([0,-60,0]) MetricBoltSet(6, 8);
+  translate([0,-80,0]) MetricBoltSet(8, 8);
+
+  translate([0,25,0]) MetricCountersunkBolt(5, 10);
+  translate([23,18,5])
+    scale([1,1,-1])
+    CountersunkClearanceHole(5, 8, [7,7,0], [0,0,0])
+    cube([14, 14, 5]);
+
+  translate([70, -10, 0])
+    RodStart(20, 30);
+  translate([70, 20, 0])
+    RodEnd(20, 30);
+
+  translate([70, -45, 0])
+    MetricWoodScrew(8, 20);
+
+  translate([12, 50, 0])
+    union() {
+      translate([0, 0, 5.99])
+        AugerThread(15, 3.5, 22, 7, tip_height=7);
+      translate([-4, -9, 0]) cube([8, 18, 6]);
+    }
+}
+
+
+Demo();
+
+//MetricBoltSet(6, 8, 10);
+