step_5.scad

difference(){
    cylinder(2, 5, 5, false, $fn=360);
    union(){
        translate([2,2,-1])  cylinder(5, 1, 1, false, $fn=360);
        translate([-2,2,-1])  cylinder(5, 1, 1, false, $fn=360);
        translate([2,-2,-1])  cylinder(5, 1, 1, false, $fn=360);
        translate([-2,-2,-1])  cylinder(5, 1, 1, false, $fn=360);
    }
}