Question 1160912
<pre>
Here's the picture for Ikleyn's solution.  She beat me posting.
The width is w, and the length is w+9 inches.  We cut out the 
4 green 4 in. by 4 in. squares at the corners and fold up the 
sides and tape the edges to make an open-top box 4 inches high. 

{{{drawing(400,3400/13,-3,23,-3,14,
line(4,0,16,0), line(4,0,4,4), line(0,4,20,4),line(16,0,16,4),
line(0,4,0,7),line(4,0,4,11),
locate(6,4,matrix(1,3,length,""="",w+9)), locate(16.2,6,w),locate(18,4,4),
green(line(0,0,0,4), line(0,0,4,0), line(16,0,20,0),line(20,0,20,4),
line(0,7,0,11), line(0,11,4,11),
line(16,11,20,11),line(20,11,20,7)),
line(0,7,4,7),line(0,7,20,7),line(16,4,16,7),line(16,7,20,7),line(20,4,20,7),
line(4,7,4,11),line(4,11,16,11),line(16,11,16,0),line(4,11,16,11)  )}}}

Edwin</pre>