What type of additive manufacturing material typically requires health and safety measures due to potential hazards?

Liquid photopolymer is the correct answer because it is a material used in processes such as resin-based 3D printing, where liquid resins are cured using UV light. These resins can pose health hazards if safety precautions are not followed. For instance, they may emit harmful fumes during the curing process, and direct contact with skin can lead to irritation or adverse reactions.

Proper ventilation, the use of personal protective equipment (PPE) like gloves and goggles, and safe handling practices are essential when working with liquid photopolymers to mitigate these health risks.

While PLA filament and cardboard sheets are generally considered benign and safe to handle, they do not usually require extensive safety measures. Metal powders also have associated hazards, such as flammability or toxicity, but liquid photopolymer specifically requires focused health and safety practices due to the nature of its chemical composition and the risks involved in its usage.