Not sure what you are thinking of, but if the case have big enough mesh/holes on the side of the case, there won't be much air suction through the floppy port.

Case is from a ~2008 era Acer Aspire M5640 with newer guts, which happens to have a door slide mechanism that covers the two external 3.5" bays with semi-transparent plastic, and an array of top-mounted USB 2.0 ports.

It's probably one of the nicer tool-free OEM mATX cases out there - no nonstandard parts, edges aren't sharp, and generally easy to route cables in.