x = 30;
y = 20;
z = 10;
offset = 4;

sphere ( d = z, $fn = 128);

translate([0, 0, z * 2]) sphere ( d = z, $fn = 128);

translate([z, 0, 0]) cube ([x/2, y/2, z/4], center = false);

translate([x, 0, 0]) rotate([45, 0, 0])cube ([x/2, y/2, z/4], center = false);