Hate dusty cases? Then you hate dusty rooms! I found a really nice replacement to a HEPA quality air filter. Take a box fan and then buy a 3M Filtrete 20x20x1 Ultra allergen Filter and buy some ( about three ) really big rubber bands and some 20~22 inch strips of foam, like the one you use as a air filter on 80mm fans ( kind you can wash). Hot glue the strips of foam to each edge of the fan so they create a seal in-between the filter and the fan. Place your virus stopping, dusty air cleaning filter and put behind the fan where it intakes air secure with the big rubberbands and voila! HEPA quality room air filter! Just make sure the foam is making a seal in-between the fan and the filter.