There are two types of extrusion-based 3D printing. FDM is the most common as it is cost-efficient and uses thermoplastics. Thermoplastic polymers such as polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), and poly(lactic acid) (PLA) are used as a drug carrier and require thermo-resistant drug molecules. PAM requires lower temperatures than FDM to print products, allowing for desired viscosity during drug formulation. A paste or gel that is shear-thinning is often ideal as the shape and structure may be retained after protrusion through a printer nozzle. PAM does require a drying time unlike FDM, during which the product can deform or shrink.