you can buy sheets of phot etched grills/gratings. try googling it or search on a modelling site such as netmerchants.
what scale is that? it looks great!
the p/e stuff might not be what your after but if you can post a picture of what your looking for i might be able to help further. there are lots of different styles of p/e meshes/gratings so you might find what your looking for.
here are a few examples:
Netmerchants > Plastic Scale Model Shop Home > Your Search Results
Richard