Harc Lee has proposed a new Coke can free of environmentally harmful inks. The concept relies completely on the embossing of the can. It's difficult to look at this and not worry about how it would translate to Zero and Diet Coke. Nonetheless, it's nice testament to how iconic Coke is in this moment in time and it's cool to see other designers playing with that iconic quality.
Dieline Link: TheDieline.com: Package Design: Colorless Coke Can
Harc has some other neat concepts in his portfolio here: http://www.behance.net/HarcLee
CG
