CNFs have two key properties that make them highly effective reinforcements in AJP inks for forcegenerating materials. First, the crystalline regions of cellulose exhibit an exceptionally high elastic modulus due to their unique packing density, rendering them extremely stiff. Their axial modulus surpasses that of Kevlar and is comparable to highly engineered materials like carbon fibers. This stiffness enables significant force generation when the material swells upon water absorption. Second, CNFs are highly hygroscopic because of abundant surface hydroxyl groups and the exponential increase in surface area at the nanoscale. Nanoscale cellulose fibers can expand in diameter by up to 45% upon water exposure. This large surface area enhances reactivity with water molecules, leading to rapid and substantial swelling. Wood, known for its high swelling entropy and ability to perform significant mechanical work, exhibits swelling pressures up to 91 MPa, with theoretical maxima of 158 MPa. As isolated forms of the stiffest and most hydrophilic component of wood, cellulose nanomaterials may achieve even higher theoretical swelling pressures and force generation. Combining CNFs with MXene ink allows light to be converted into heat, which can be used to control the water content in the material, enabling tunable actuation.