radius = 10.25;
wall = 8;
c_wall = 6;
screw_r = 4.5;
screw_insert_r = 25;
h = 60;

module support() {
    difference() {
        hull() {
            cube([(radius+c_wall)*2, wall, wall]);
            translate([radius+c_wall, 0, h - radius - c_wall]) 
                rotate([-90, 0, 0]) cylinder(r=radius+c_wall, h=wall);
        }
        translate([radius+c_wall, -1, h - radius - c_wall])
            rotate([-90, 0, 0]) cylinder(r=radius, h=wall+2);
    }
}

union() {
    difference() {
        cube([(radius+c_wall)*2, (screw_insert_r+wall+2)*2, wall*2]);
        translate([radius+c_wall, screw_insert_r+wall+2, -1])
            cylinder(r=screw_r, h=wall*2+2);
        translate([radius+c_wall, screw_insert_r+wall+2, wall])
            cylinder(r=screw_insert_r, h=wall+1);
    }
    support();
    translate([0, wall + screw_insert_r*2 + 4, 0]) support();
}