From another comment:

>Presumes the floor (or other surface) is perfectly flat...

with your reply to that comment:

>And that the floor will attenuate any reflected EMP/signal from underneath (should be small in a basement, but ...)

I believe that I addressed those issues in my reply to the other poster.

>Trash can lids are usually not so flat, which makes the whole thing wobbly.

Very true but simple to accommodate for even if the wobble has zero effect on its signal attenuation characteristics. If the can that I linked topples in the wind it will not affect the seal at all. That is a very durable can with a dependable grip on the lid.

>The ones you linked lack a handle on top, but it's a common feature on metal cans.

True that handles are common on trash cans. I buy that trash can specifically because it does not have a handle and therefore it has no holes or slits in the lid. The dish shape makes it suitable for use as a shallow, very durable bird bath or water feature for attracting bees and other insect pollinators. When you have a lid like that one you can get a cheap solar-powered floating aerator/sprayer and add a few rocks and a piece of weathered driftwood for perches. Bees, wasps, dragonflies, butterflies, moths, etc will make good use of the small fountain feature. Fountains that I have scattered on my place draw all kinds of insects and birds. A few weeks ago I had a snake slither over to one of them and spend a few minutes dipping its chin for a cool drink.

I plant trees and other plants in the can and use the lid for water features.