Interesting experiment. I think any kid at some point probably tried the to achieve the same goal, except back then it made the most sense to try and bash the outside layers off to expose the cool design (or animals) inside.
Someday maybe one of the high end marble glass makers will find a medium to carry the inner pattern, that can later be dissolved (chemically or whatever) to leave just the inner pattern intact. Fragile and beautiful.
And then somebody might come up the idea of encasing that fragile and beautiful pattern in a durable layer of clear glass and here we are again.. (and the marbles keep on rolling)