A design attempt on the Clean Tech style. The customer's demand is to make a portable electric toothbrush with a sense of science and technology. The design is inspired by the energy bar of science fiction style. The original strip-shaped circuit board of the internal structure of the toothbrush is arranged and designed as the appearance element, and the outside is wrapped with frosted translucent plastic and matched with matte metal texture. The transparent upper cover can directly see the brush head of the toothbrush. The top of the upper cover is provided with air holes. The transparent material can prevent bacteria from growing in the brush head cover. The top of the brush head cover corresponds to the decorative parts at the bottom of the toothbrush, which also makes the overall design language more continuous. The most difficult part of the design process is the processing of the circuit board. Because it is necessary to consider the general arrangement of the circuit boards of the actual products, two methods were prepared at the beginning of the design. The preferred treatment method is to first discuss with the engineer to judge the feasibility, and then redesign the exposed part of the circuit boards of the scheme with reference to the arrangement of the circuit boards of the existing products. It is considered that if the effect of this treatment method is not ideal, a decorative circuit board will be considered. The final verification of the preferred treatment is feasible and the effect is more real.