Mike Reynolds [0] of "Garbage Warrior" and "Earthship" fame has been reusing empty plastic waste bottles in a similar fashion for decades. The cement forms a m

Mike Reynolds [0] of "Garbage Warrior" and "Earthship" fame has been reusing empty plastic waste bottles in a similar fashion for decades. The cement forms a matrix around vacancies created by the bottles which become a permanent part of the structure. He's also used aluminum cans and glass bottles in a similar fashion. Colored glass bottles can produce visual results resembling stained glass, it's interesting. But these are hand laid like brick laying, so not quite what you're thinking with the ping-pong balls. [0] https://en.wikipedia.org/wiki/Mike_Reynolds_(architect) https://en.wikipedia.org/wiki/Mike_Reynolds_(architect)