Update
Mesh
Clear;
all = Tuples[{0, 1, 2}, 3];
erase = Tuples[{0, 2}, 3];
rest = Complement[all, erase];
Graphics3D[{Lighting -> "Accent", EdgeForm[Blue], FaceForm[],
Cuboid[#] & /@ rest}, Boxed -> False]
Solid
Clear;
all = Tuples[{0, 1, 2}, 3];
erase = Tuples[{0, 2}, 3];
rest = Complement[all, erase];
Graphics3D[Cuboid[#] & /@ rest, PlotRange -> All]
2D
BTW,we can also draw the 2D version.
Clear;
all = Tuples[{0, 1, 2}, 2];
erase = Tuples[{0, 2}, 2];
rest = Complement[all, erase];
Graphics[{EdgeForm[Blue], FaceForm[Opacity[0.1]],
Rectangle[#] & /@ rest}]
Original
Clear;
vertexs = Tuples[{-3, 3}, 3];
ineqs = Norm[{x, y, z} - #, ∞] >= 2 & /@ vertexs
reg = RegionPlot3D[And @@ ineqs, {x, -3, 3}, {y, -3, 3}, {z, -3, 3},
Lighting -> "Accent", PlotPoints -> 80, Mesh -> None,
PlotStyle -> Gray, BoundaryStyle -> {Thick, White}, Boxed -> False,
Axes -> False]
(*Needs["NDSolve`FEM`"]
reg // DiscretizeGraphics // ToElementMesh
%["Wireframe"]*)