This paper presents an experimentally validated UV photolithography and electroforming (UV-LIGA) manufacturing technique to produce a high-precision, metal-only 64x64-element transmit antenna array for applications in the 1 THz WR 1 band. The technique presented separates the manufacturing process into three parallel stages: film fabrication, electroforming and assembly. A phasing element antenna design is manufactured with a five-layer folded-slot structure with an air-filled spacer layer in between the folded slot slices. The electroforming time accurately controls the spacer layer air gap for the desired antenna performance.