We present a deep X-ray mask with integrated bent-beam electrothermal actuator for the fabrication of 3D microstructures with curved surface. The mask absorber is electroplated on the shuttle mass, which is supported by a pair of 20-mu m-thick single crystal silicon bent-beam electrothermal. actuators and oscillated in a rectilinear direction due to the thermal expansion of the bent-beams. The width of each bent-beam is 10 mu m or 20 mu m and the length and bending angle are 1 mm and 0.1 rad, respectively, and the shuttle mass size is 1 mm X 1 mm. For 10-mu m-wide bent-beams, the shuttle mass displacement is around 15 mu m at 180 mW (3.6 V) dc input power. For 20-mu m-wide bent-beams, the shuttle mass displacement is around 19 mu m at 336 mW (4.2 V) dc input power. Sinusoidal cross-sectional PMMA microstructures with a pitch of 40 mu m and a height of 20 mu m are fabricated by 0.5 Hz, 20-mu m-amplitude sinusoidal shuttle mass oscillation.