group() {
	difference() {
		union() {
			cube(size = [30, 30, 30], center = true);
			cube(size = [40, 15, 15], center = true);
			cube(size = [15, 40, 15], center = true);
			cube(size = [15, 15, 40], center = true);
		}
		union() {
			cube(size = [50, 10, 10], center = true);
			cube(size = [10, 50, 10], center = true);
			cube(size = [10, 10, 50], center = true);
		}
	}
}

