Yes.

In practice it probably depends on the temperature, but lets assume not real air, but an ideal gas. Then, all you have to do is to increase the pressure enough for it to have the same (or infinitesimally higher) density than the marble: at this point [buoyancy][1] equals the weight of the marble and it can "float".

That will not depend on the shape or size of the object inside, only on its density.

As for the spread you describe, unless there's some sort of flow in the container, there has to be some effective attraction to the wall.

**Edit**: it's important to note that, if the key concepts are not only *pressure* and *flotation*, but also *air*, than, as many pointed out, air cannot be made as dense as a typical marble without changing phase (and or melting the marble).


  [1]: https://en.wikipedia.org/wiki/Buoyancy