Tires, 2-liter soda bottles, pallets, even glass bottles can be re-purposed as construction materials for sustainable homes.
Even stripping milk cartons for the HDPE to use as shingles or Siding is practical. Same goes for the 2-liters, though...
With the 2-liter soda bottles, they can be filled with dry sand and used as masonry blocks. They have fantastic insulating value and make sturdy walls.
And rammed-earth in old tires is the founding basis of Earthship construction.