A materials kit for three-dimensional (3D) printing can include a powder bed material comprising thermoplastic polyurethane particles and a fusing agent including a radiation absorber to selectively apply to the powder bed material. The thermoplastic polyurethane particles can have an average particle size from about 20 μm to about 120 μm and a melting temperature of from about 100° C. to about 250° C., wherein the thermoplastic polyurethane particles include polyurethane polymer strands having an average of about 10 wt % to about 30 wt % hard segments based on a total weight of the thermoplastic polyurethane particles. The hard segments can include a symmetrical aliphatic diisocyanate and a symmetrical aliphatic chain extender that are polymerized into the thermoplastic polyurethane particles.