So, as promised: a few screenshots with notes. Here I remodeled the ventilation meshwork at the side of the roman 5. Step one, the model with the old one removed. Step two, model only two wooden beams, uv-map them, use mirror-modifier (for right-left symmetry). Step three, use the array modifier to have as many of them at hand as one wishes. Step four, use the curve modifier, together with a curve (nurbs in this case), to have the mesh fit the opening. Also change the array modifier from fixed count to fit curve length. Step five, apply modifiers and manually adjust vertices when needed (use proportional editing to save time). Step six, example bake of this high quality 3D model to an incomplete low poly mesh with only 12 polys for demonstration. As you can see, simple baking already produces pretty good results, however in this case some texture editing would be required to really have convincing textures.