Hm, ya somebody told me the freezer was better than microwave. I should probably just order some stockpiles of mesh wire?
A freezer would be unlikely to work. https://yewtu.be/watch?v=PlB4LGLtRQM
But wrappen in aluminum foil, in a galvanized trash can with foil tape holding the lid on... now you're talkin'!
Discussion
RF is part of it, and an earthed faraday cage with no holes will work for that
but there is also X and gamma rays, for those you need lead or tin or similar
most of the "foil" you see on space things is tin foil, it blocks x-rays with a lot less weight than lead, though it's not as effective
Good stuff