Well, inspired by a question on the Week Day Challenge (www.blenderchallenge.com), i write this short tut, that i think relies on how good topology enhances modeling.
C&C are welcome, and here it goes:
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Make a plane.
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delete the face, leaving just edges. (First delete one edge, and then select the two open points and press Fkey)
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extrude only the edges, and don’t move them, just scale them. Extrude and scale the new edges to get it like the figure.
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press F to fill the square hole in the middle. Then with Ctrl+R add two cuts horizontal and two cuts vertical.
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tweak points (i just scaled them) to get the X shape as you want. Select the faces that will conform the hole.
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Extrude them a little.
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Subsurf. You can tweak this a little by adding more loop cuts where you need, pressing Shift+E to control the creasing of the subsurf, etc.
For the render i’ve added two loop cuts and extruded the external sides to get something similar to a box. No more detail 
Hope you like it!
Martín
