group() {
	linear_extrude(height = 20, center = false, convexity = 1, scale = [0.5, 0.5], $fn = 40, $fa = 12, $fs = 2) {
		offset(delta = 10, join_type = round, miter_limit = 2, $fn = 40, $fa = 12, $fs = 2) {
			square(size = [50, 50], center = true);
		}
	}
	multmatrix([[1, 0, 0, 0], [0, 1, 0, 0], [0, 0, 1, 20], [0, 0, 0, 1]]) {
		linear_extrude(height = 20, center = false, convexity = 1, scale = [1, 1], $fn = 40, $fa = 12, $fs = 2) {
			group() {
				difference() {
					offset(delta = 1, join_type = miter, miter_limit = 2, $fn = 40, $fa = 12, $fs = 2) {
						group() {
							circle($fn = 40, $fa = 12, $fs = 2, r = 15);
						}
					}
					offset(delta = -1, join_type = miter, miter_limit = 2, $fn = 40, $fa = 12, $fs = 2) {
						group() {
							circle($fn = 40, $fa = 12, $fs = 2, r = 15);
						}
					}
				}
			}
		}
	}
%	cylinder($fn = 40, $fa = 12, $fs = 2, h = 100, r1 = 14, r2 = 14, center = false);
%	multmatrix([[1, 0, 0, 0], [0, 1, 0, 0], [0, 0, 1, 100], [0, 0, 0, 1]]) {
		sphere($fn = 40, $fa = 12, $fs = 2, r = 30);
	}
}