Abstract Fused deposition modeling (FDM) parts were enhanced by post-processing to improve surface quality. After reforming with loading and heating applied, the surface can reflect light. Hence, FDM parts with reflective surfaces fabricated from the regular FDM process can be used as optical elements. In printed specimen tests, one surface of the specimen is put on a sheet glass, and both are heated and pressured together to reform the surface of FDM parts. After testing several materials, almost every printed specimen is affected by post-processing, and the optical reflectivity of the FDM parts is increased. However, shrinkage causes a reduced height, and the shape of the FDM parts is deformed dramatically in higher temperature heating condition. The proposed post-processing method improves the surface of FDM parts, and a fabrication process combining this method and investment casting to manufacture optical CCR arrays (possibly with smaller pitches than the original purchased acylic model) was established.