\( \DeclareMathOperator{\abs}{abs} \newcommand{\ensuremath}[1]{\mbox{$#1$}} \)
(%i1) load(draw)$
(%i2) F(x, y, z) := x^2 -y^2 -z^2 - 5$
(%i3) F_d(x, y, z) := abs(
   diff(F(x, y, z), x, 1) -
   diff(F(x, y, z), y, 1) +
   diff(F(x, y, z), z, 1)
)$
(%i4) implObj: implicit(F(x, y, z), x, -10, 10, y, -10, 10,
   z, -10, 10)$
(%i5) wxdraw3d(
   x_voxel=40, y_voxel=40, z_voxel=40,
   enhanced3d=[F_d(x, y, z)*0.25 + 0.5, x, y, z],
   colorbox=false,
   palette=gray,
   implObj
)$
\[\tag{\%{}t5}\label{t5} \]  (Graphics)

Created with wxMaxima.