We present the fabrication, numerical simulation and optical characterisation of micro- and sub-micrometer "Yablonovite" structures. The structures are fabricated in PMMA resist by three consecutive exposures through a triangular lattice of holes. The sample is tilted by 35.26° with respect to the incoming X-ray synchrotron beam and rotated by 120° between each exposure. Submicrometer structures showing up to six (111) periods are fabricated with a good reproducibility and a large process latitude in 6.2 mm PMMA thick resist. In the quest of a complete photonic band gap, we also present two simple and low-cost ways to replicate the 3D sub-micrometer structure in a high refractive index material. Results of copper electrodeposition and titanium oxide deposition in the resist template will be discussed.