How to Make a Floating Shelf in on Shape

I made a floating shelf.

3-d print filament

First I selected to make a new sketch and selected the top plane. I then selected the center point rectangle started at the origin and made the rectangle 4 inches by 10 inches. I then selected the extrude tool and extruded the rectangle by 2 inches.

I then selected the extrude tool and extruded the rectangle by 2 inches.

Then I made a CenterPoint circle on one side of the rectangle.

I then extruded the center point circle by 2 inches.

I then selected the mirror tool selected the center point extruded circle and mirrored it to the other side so now there are two center point extruded circles.

I made another sketch and made the radius of the circle 0.711 inches.

I made a rectangle that was made on the axis the dimensions were 4.629 inches by 1.422 inches. I then extruded the rectangle by 0.1 inches.

I lastly mirrored the extruded rectangle on the axis it was made and it was then one big connected rectangle.