thickness = 3;
inside_dia = 67;

height = 60;

module piece(){
    translate([0,0,height/4])
    difference(){
        cylinder(r=inside_dia/2+thickness, h=height/2, center=true);
        translate([0,0,thickness])
        cylinder(r=inside_dia/2, h=height/2, center=true);
        translate([0,0,-height/4+thickness/2-0.1])
        cylinder(r1=inside_dia/2-thickness, r2=inside_dia/2, h=thickness+0.3, center=true);
    }
}

$fn=150;
union(){
    piece();
    rotate([180,0,0])
    piece();
}