MovieWeb seems to have an “inside source” that knows the plot of Amazing Spider-Man 2 and 3. They’re reporting that Harry Osborn as played by Dane Dehaan will suit up as the Goblin in the second sequel, not Norman as played by Chris Cooper. They also have a mole that describes the goblin suit in detail.
Green Goblin’s suit will be made up entirely of matte black armor that resembles a hi-tech motocross suit. The suit will remain open-faced, and there will be no helmet at all. Norman will have green hair that is spiked high up.
In his ears, he will be wearing a Bluetooth device that will make it look as though he has the Green Goblin’s signature pointed ears, the same way Selina Kyle’s goggles worked in creating the illusion that she had cat ears. The back of the armor has a spine. At the moment, there are no green accents. From a distance, you’d be forgiven for thinking that Tony Stark’s signature Mark XLII armor had been painted black.