%var x y z
g = golden_ratio; r = 4.77
p = 2 - (cos(x + g*y) + cos(x - g*y) + cos(y + g*z) +
         cos(y - g*z) + cos(z - g*x) + cos(z + g*x))
g = implicit_plot3d(p, (x, -r, r), (y, -r, r), (z, -r, r),
                plot_points=30, color='blue', mesh=1, opacity=.7)

g + cube(size=4, color='green', opacity=.6, mesh=3)