Commenting on the idea of changing the air holes, that could work for either the intakes OR the outputs, depends on how the fan is built. The exit port might be easier to cut out with a dremel or something, then tape over the old exit hole. The intake zones tend to be large and any kind of obstruction rather than a fully open face would not be recommended.
They exist, but maybe only for industrial use and not so compact. Look for "clockwise".
You could carve the back side of a normal blower with some openings (make a grid out of it) and obstruct the original inlet (or leave both open...).