Here is a "mod" that I use that works very well and keeps most of the dust out for those who run with the side off the case. Go to your local Lowes, Home Depot, whatever and buy some window type AC filters. They are very thin and look like sponge. Also buy a roll of velcro tape. Place the prickly side of the velcro around the edges of your case. Stick the filter to it and trim to fit. If your case is larger than 1 filter take 2 (or more if needed) overlap them about 1/2 inch and glue them together. It ain't pretty but it works.
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