I picked up some tailor made mesh filters for my case from
https://www.demcifilter.com/
I had been contemplating buying some kind of mesh product and rolls of magnetic strips to build some filters to put over the open areas on my CoolerMaster HAF XB Evo case. When all said and done I probably would have spent around $20-30 for material to have it shipped to me, then a few hours of my time measuring things out and constructing my own....
I just happened to stumble across custom built ones for my case from demcifilter. The set of filters for my case was about $38 with shipping. Cost just a little more than doing them myself, but saved me time of having to make my own.
Having a Siberian husky there is constant fur and pet dander, even with vacuuming every other day. These filters have done an amazing job keeping so much unnecessary dust and pet hair out of my system over the past 3 months since I got them. The inside of the case still looks as good as it did before I started using the filters with my new hardware. You can't keep out all the dust, but so far they've helped cut down on I'd say 95% of it.
When I do need to clean the filters off, I remove them before I go to bed and simply run them under the kitchen faucet to clean them off and let them air dry over night. The next day I put them all back in before I turn the computer on. So far this beats having to remove the case fans every 6-8 months to blow them off or brush them out due to the build up of dust that accumulates on them.
Only thing I wish was better about the filters was the magnetic strip strength. They hold in place pretty good as they are, I just wish the magnetic strength was a little better.