Inlet Throat for Samsung DVD Home Cinema System HT-TX35

I put my Samsung DVD Home Cinema System HT-TX35 AUX to a closed IKEA TV-shelf. It was too warm and no air moved inside.
I drilled holes to the back of the shelf but still too warm. I designed this inlet throat measuring 5cm x 5cm rectangular base with 4cm x 4cm screw holes so the unit can suck air from the outside of the shelf. You may use this for you other project.
Cylinder wall: 1mm
Base: 1mm
Cylinder diameter: 47mm