$fn = $preview? 32 : 72;

// arm 1
rotate([0,0,90]) arm1();

// arm 2
thinkness=3;
width = 10;
bore = 4;
rotate([0,0,180]) {
translate([0,0,thinkness])  arm2();
translate([0,0,-thinkness]) arm2();
}

// arm 3
translate([-25,0,0]) rotate([0,0,90]) arm3();

// arm 4
translate([0,65,thinkness]) arm4();
translate([0,65,-thinkness]) arm4();

module arm(holes, width, thinkness, bore){
    difference(){
        hull(){
            cylinder(h=thinkness, d=width,center=true);
            for(hole = holes){
                translate([hole,0,0]) cylinder(h=thinkness, d=width,center=true);
            }
        }
        for(hole = holes){
          translate([hole,0,0]) cylinder(h=thinkness*2, d=bore,center=true);
        }
    }
}

module arm1(){
  arm([0,65],width=10, thinkness=3, bore=4);
}

module arm2(){
arm([0,25],width, thinkness, bore);
}

module arm3(){
arm([0,65],width=10, thinkness=3, bore=4);
}

module arm4(){
arm([-25,0,50], width, thinkness, bore);
}