thickness = 2;
toprad = 15;
bottomrad = 10;
radius = 25;
height = 30;
rotate_extrude(angle=360, $fn=360){
    polygon([
        [toprad, 0],
        [bottomrad, height],
        [bottomrad+thickness, height],
        [toprad+thickness,thickness],
        [radius-thickness,thickness],
        [radius-thickness,height],
        [radius, height],
        [radius,0],
        [toprad,0]]
    );
}