OpenSCAD source code: Tour Easy Zzipper Fairing mount blank plates

Fairing Flashlight Mount.scad: Plate Blank excerpt

//- General plate shape
// Centered on the hole for the fairing bracket

Plate = [100.0,30.0,6*ThreadThick + Bracket[2]];
PlateRad = Plate[1]/4;

echo(str("Base plate thick: ",Plate[2]));

module PlateBlank() {

  difference() {
    translate([BracketHoleOC,0,0])
      intersection() {
        translate([0,0,Plate[2]/2])                           // select upper half of spheres
          cube(Plate,center=true);
        hull()
          for (i=[-1,1], j=[-1,1])
            translate([i*(Plate[0]/2 - PlateRad),j*(Plate[1]/2 - PlateRad),0])
              resize([2*PlateRad,2*PlateRad,2*Plate[2]])
                sphere(r=PlateRad);                           // nice rounded corners!
      }
    translate([2*BracketHoleOC,0,-Protrusion])                // screw holes
      PolyCyl(BracketHoleOD,2*Plate[2],8);
    translate([0,0,-Protrusion])
      PolyCyl(BracketHoleOD,2*Plate[2],8);
  }
}

More details on my blog at http://wp.me/poZKh-6UL