$fs=0.25;$fa=6;
union() {
difference(){cube([55,86,4],center=true);
translate([0,0,1.2])cube([52.6,83.6,4],center=true);
}translate([-29,-34.4,0])union() {
rotate([-180,-90,180])difference(){union() {
cube([4,16.2,3],center=true);
translate([0,0,1.5])rotate([90,0,0])cylinder(h=16.2, r=2, center=true);
}
translate([0,0,1.5])rotate([90,0,0])cylinder(h=17.2, r=1, center=true);
}translate([0,34.4,0])rotate([-180,-90,180])difference(){union() {
cube([4,16.2,3],center=true);
translate([0,0,1.5])rotate([90,0,0])cylinder(h=16.2, r=2, center=true);
}
translate([0,0,1.5])rotate([90,0,0])cylinder(h=17.2, r=1, center=true);
}translate([0,68.8,0])rotate([-180,-90,180])difference(){union() {
cube([4,16.2,3],center=true);
translate([0,0,1.5])rotate([90,0,0])cylinder(h=16.2, r=2, center=true);
}
translate([0,0,1.5])rotate([90,0,0])cylinder(h=17.2, r=1, center=true);
}}
}