i) It is multi-functional and simple as it can be used to brush things and peel skins. It is simple as you can see from the picture above so people will easily know how to use the brush. The grip of the brush is not good enough.
ii) They must think of whether it is user-friendly, how can it be stored, and whether the design is able to perform all its functions properly.
iv) The grip can be made better by designing the surface of the handle to follow the contours of the hand, together with the corrugation, it would be very easy to grip.
(the sketch of the improved version of the brush is above)