Here's how: Aluminum window screen, available at most hardware stores, TOTALY blocks this type of microwave radiation. A single layer is enough. One could simply tape a big piece over the whole thing, but I wanted something more user-friendly and more long-lived. First, wear some leather gloves. This material is hazardous and WILL poke your hands but GOOD countless times if you don't ! I used sheet metal shears to cut it, but some good heavy kitchen shears will work. You may find them more dull afterward though. It's pretty easy to cut. I used a hot glue gun with clear sticks to bond the base to the cylinder, and shown in the photos. I used some small aluminum pop-rivets to attach the sign, and nylon thread (waxed) to attach the "lid".