It is well known that endohedral fullerenes have potential quantum computing applications example 1,example 2, and example 3. But, currently they are too expensive, around $167 million per gram at this time. A huge part of the cost is currently because only about 1/650,000 fullerenes have an atom trapped in it.
But looking at this made me wonder if there was a known way to form a stable polyhedral molecule where each side contains a crown ether, or a single crown ether surrounded by carbon atoms. This way it might be much easier trap an atom inside.