Dust Proof Cases

I am a Carpenter. Minute pieces of sawdust are always my worst enemy everyday. I have the otterbox defender, but that lets sawdust in. Eventually scratches my glass because it rubs between the screen protector.

I need a case where all ports are fully covered, or plugged. I will sacrafice some of the use of the phone for dust proof quality. There are finally some other companies making cases like these. I wanted to get some opinions of anyone who has tried some dust proof cases.