Point(1) = {0, 0, 0};
line[] = Extrude {1, 0, 0} { Point{1}; };
surface[] = Extrude {0, 1, 0} { Line{line[1]}; };
volume[] = Extrude {0, 0, 1} { Surface{surface[1]}; };
Physical Surface(1) = {volume[3]}; // Right
Physical Surface(2) = {volume[5]}; // Left
Physical Surface(3) = {volume[0]}; // Upper
Physical Surface(4) = {surface[1]}; // Lower
Physical Surface(5) = {volume[2]}; // Back
Physical Surface(6) = {volume[4]}; // Front
Physical Volume(1) = {volume[1]};
