There was a major issue with marbled case polystyrene that was not technology-related. When a black casing was made after a white casing on the same machine, a small amount of white plastic remained in the machine from the previous job. On this account, the black plastic that was subsequently introduced into the machine become mixed with this residue, which was then injected out for a certain time. This white-black mixed material was initially discarded. However, the mixed material that had formerly been discarded was utilized and used in radio casings. The idea of recycling can be said to have originated from a wonderful casing that had the appearance of marble where complex black curves were mixed into a white background.