To keep my wife and her stuff out, I use enamel alkyd high fumes paint regularly. She comes out a lot to see if their is room for various items, then I crack the paint can open, back to the house she goes…. That approach might not work with the in law suite above your shop tho. The only real problem with my technique is if it is NFL playoff season and I have a fresh coat of paint on something the boys can get a little red eyed….lol

CHRIS, Charlottetown PEI Canada. Anytime you can repurpose, reuse, or recycle, everyone wins!