The one I would argue against here is the ejector pin marks. If you have ejector pin marks visible of the "outside" of your component then something has gone w

The one I would argue against here is the ejector pin marks. If you have ejector pin marks visible of the "outside" of your component then something has gone wrong in the design process. Injection moulding tools have two sides, a static and a moving side. The static side will contain the "gate" where the molten plastic is injected. You would almost always expect the moving side to be the visible side of the component, it tends to be simpler in features and polished. The static side will have many mechanical features such as ribs for strengthening, or snaps/bosses for securing other components. When the tool opens the part will stay in the static half, then be ejected by the ejector pins. All these should be hidden on the inner side of the component. The exception to this is components with no inside/outside, the sort of thing that may be a visible component in a hinge. What is much more likely to be an issue for someone trying to imitate Apple are visible seams or witness marks on side actions on the tool. A side action is where you have a part of the tool move at 90deg (or some other angle) to the main opening action. This lets you build in undercuts, or have holes in the side. (There are also collapsible cores, but these tend to be on the inside of a part) The witness marks where the side actions fit against the rest of the tool are almost impossible to hide, you even sometimes see them on some Apple products. You need very very tight tolerances through the whole stack to ensure they are so small you hardly notice them. Well designed plastic component are created when the engineer/designer has a thorough understanding of the manufacturing process and are thinking about how the tooling will work while they are designing the part. The issues arise when you design a part, then hand it over to someone else to design the tool with no input into the design process. Edit: Another one I used to have customers ask for was to have "no seam" between two plastic parts "like Apple". Fitting two plastic parts together with no seam is basically impossible unless you are Apple. It's why you almost always see a ~1mm uniform gap between the parts, it helps to hide any misalignment and gives you a closing tolerance between the parts.