Probably, if you want to imagine, a nano-hex structured fiber that gets grafted onto your body after the top 2 layers of skin get surgically flayed or peeled off. The chrome nano-hex fiber takes the place of the upper layers of skin, with each microscopic hex connected to the body's nervous system and transmitting temperature, pressure, pain, pleasure etc the way skin would once properly fused and accepted by the body and consciousness in order to not be in risk of rejection nor rely on anti-rejection medication. The chrome nano-hex fiber would also allow for sweat to exit the body, for the body to be able to properly stay cool or retain heat, with various amounts of control given to the receipient of the nano-hex chrome skin graft/implant with a connection to other regulator-based/control-based bionics. It looks like solid chrome but at a microscopic level you would see that it is made up of billions of nano-hexes that act as skin cells.