Are the boxes of equal size, color, stroke width and orientation? So for example you would represent the upper, horizontal line of the E with 7 boxes in width, 3 in height, each with equal spacing?
You might either do it by cloning 2, 3 sample squares, positioning them and then look at the XML and generate all the square clones with a short script.
Or, if the background is for instance white, spread your squares which needn't be in such a strict order and hide some of them below 2 big white squares or pick the squares to delete with drawing the mouse over the black (colored) squares to be removed.
For the first E, I made 7 clones, aligned them at top with the align tool, then equal spacing, then grouped the seven and made 9 copies of the group, aligned the groups left, equal vertical spacing, then broke 4 of the groups and removed the 5 superflous squares of these lines 3, 4, 7 and 8.
For the second version, I made a clone, used the spray tool to distribute the squares on the field. Used the align tool again, since I use the german version I describe the location of the tool: The 3rd group, ordering or placement, the 2 most right options, random distribution and unclump.
Then I made 2 squares, which roughly fit into the space at the E at the left, moved them to the right, and selected a space a little wider and deleted all the so marked objects.