var('y z')

(y, z)

implicit_plot3d(x^2+y^2+z^2+cos(4*x)+cos(4*y)+cos(4*z)-0.2,(x,-2,2),(y,-2,2),(z,-2,2),
                plot_points=100,color='lemonchiffon').show(viewer='threejs',online=True,frame=False)