It's made of 1x1's. Except the top and bottom. Those are 32x32 baseplates.

Each 1x1 is representative of each plastic product thrown out instead of being recycled in Houston. No I am not done. Yes it is hollow, i am gonna tabulate how many "theoretical bricks" there should be, and keep duping until I am as close to the actual number i need as possible.
EDIT: Those are four giant 1x1's placed together.