Is steel, because of the number of manufactured cars. Another reason why is when we reuse or melt the steel down it doesn’t loose much of itself. The one we are all familiar with is aluminum cans and plastic bottles. I also found out its not the most recycled product but aluminum could be one of the most beneficiary to us price wise if we recycled it. Though if you do recycle the aluminum it will help with other areas of printing like markers in the ink cartridges for our field (Or any field that uses ink cartridges).