Which of the following is NOT a type of child pornography collector described in the guide?

The term "public collector" is not recognized as a type of child pornography collector in the context of the guide. The other types identified—hobbyist collectors, commercial collectors, and situational collectors—each have distinct characteristics and motivations for their collection habits related to child pornography.

Hobbyist collectors typically collect materials for personal enjoyment, often maintaining large collections and taking pleasure in the act of collecting itself. Commercial collectors, on the other hand, are focused on the financial aspect, engaging in transactions to gain profit from the distribution of such materials. Situational collectors may gather child pornography under specific life circumstances or stressors that prompt their behavior, revealing the complex motivations behind their actions.

Since "public collector" does not align with these recognized categories and lacks defined characteristics as per the guide, it is indeed the type that is not classified within the established framework of collectors described.