cover.js

function main() {
    return union(
        difference(
            cylinder({r: 25 / 2., h: 3}),
            cylinder({r: 22 / 2., h: 2}).translate([0,0,1])
        ),
        difference(
            intersection(
                cylinder({r: 20.0 / 2.0, h: 7}),
                cube({size: [20., 15, 7], center: true}).translate([0,0, 3.5])
            ),
            intersection(
                cylinder({r: 18. / 2.0, h: 7}),
                cube({size: [18., 13., 7.], center: true}).translate([0,0, 3.5])
            )
        ),
        
        difference(
            intersection(
                cylinder({r: 21.0 / 2.0, h: 0.5}).translate([0,0, 6]),
                cube({size: [21, 16, 7], center: true}).translate([0,0, 3.5])
            ),
            intersection(
                cylinder({r: 18. / 2.0, h: 7}),
                cube({size: [18., 13., 7.], center: true}).translate([0,0, 3.5])
            )
        ),
        
        difference(
            intersection(
                cylinder({r: 21. /2, h: 0.5}).translate([0,0,5]),
                cube({size: [21, 16, 7], center: true}).translate([0,0, 3.5])
            ),
            intersection(
                cylinder({r: 18. / 2.0, h: 6}),
                cube({size: [18., 13., 7.], center: true}).translate([0,0, 3.5])
            )
        ),
        
    );
}