Added GoPro screw knob and some photos

Quanum Trifecta/GoPro Screw.scad

@@ -0,0 +1,57 @@
+/*
+ * Created by:
+ * Thomas Buck <xythobuz@xythobuz.de> in June 2016
+ *
+ * Licensed under the
+ * Creative Commons - Attribution - Share Alike license.
+ */
+
+// -----------------------------------------------------------
+
+d_min = 8.7;
+d_max = 9.2;
+d_inner = 5.5;
+d_outer = 14;
+d_grip = 11;
+w_grip = 20;
+h_top = 5;
+h_mid = 35;
+h_bottom = 10;
+sphere_ratio = 1.25;
+grip_ratio = 1.75;
+grip_angle = 20;
+
+$fn = 20;
+
+// -----------------------------------------------------------
+
+difference() {
+    union() {
+        difference() {
+            intersection() {
+                translate([-w_grip / 2, -w_grip / 2, 0])
+                    cube([w_grip, w_grip, h_bottom]);
+                sphere(d = w_grip * sphere_ratio);
+            }
+            
+            for(angle = [0, 90, 180, 270]) {
+                rotate([0, 0, angle])
+                    translate([0, -w_grip / grip_ratio, -w_grip / 4])
+                    rotate([grip_angle, 0, 0])
+                    cylinder(d = h_bottom, h = h_bottom + (w_grip / 2));
+            }
+        }
+        
+        translate([0, 0, h_bottom])
+            cylinder(d = d_outer, h = h_mid + h_top);
+    }
+    
+    translate([0, 0, -1])
+        cylinder(d = d_grip, h = h_bottom + 1);
+    
+    translate([0, 0, h_bottom - 1])
+        cylinder(d1 = d_max, d2 = d_min, h = h_mid + 1, $fn = 6);
+    
+    translate([0, 0, h_bottom + h_mid - 1])
+        cylinder(d = d_inner, h = h_top + 2);
+}