Abstract: Disclosed is a method for making a part including a substrate made of a precious metal, including: a step of providing the substrate made of an alloy including between 94% and 99.5% of copper (Cu), between 0.5% and 6% of gold (Au), and between 0% and 4% of at least one added element, the substrate having a surface, called upper surface, and having a thickness of at least 100 ?m starting from the upper surface; and a step of preparing a patina bath from a mixture including at least: between 3 g and 10 g of anhydrous or hydrated copper acetate (Cu(CH3COO)2), between 3 g and 20 g of anhydrous or hydrated copper sulphate (CuSO4), and between 0.5 g and 2 g of salt (NaCl); then a step of applying the patina bath over the upper surface of the substrate. A part obtained by such a method.

Abstract: This invention relates to a mini-type electric vehicle, which is mainly used for individual person or traffic in a certain field. It includes frame, seat, front & rear wheel, driving device, battery, steering system and front wheel suspension device. A casing, where the battery is placed on, protrudes forward at the middle position of the front end of the frame; the suspension device for front wheel appears “Front convex & rear concave” shape and covers the front end of that casing, and pivots to the middle of the front end of the casing. Two front wheels are installed on the front wheel suspension device. The rear edge line of the two front wheels is located at the rear of the battery front edge; Steering system is connected to the front end of the frame and interlocks with the front wheel. Battery is installed at the front so as to balance the weight distribution, improve the driving safety, comfort and steering performance for electric vehicle.