The empty grid on the right has dimensions $(7$x$7)$ that

correspond to the bounding box of a mystery artifact.

This mystery artifact can be created in the following

manner. First, copy $($i$.$e$.,$ recreate$)$ the artifact shown

below to the grid on the right. Then add the minimum

number of cells so that the resulting artifact has

horizontal and vertical reflection symmetry,

$2-$fold rotational symmetry, and

a $7$x$7$ bounding box.The empty grid on the right has dimensions $(77)$ that

correspond to the bounding box of a mystery artifact.

This mystery artifact can be created in the following

manner. First, copy $($i$.$e$.,$ recreate$)$ the artifact shown

below to the grid on the right. Then add the minimum

number of cells so that the resulting artifact has

horizontal and vertical reflection symmetry,

$2-$fold rotational symmetry, and

a $77$ bounding box.