A reader noticed the wire grille in my half-built gray shelves and wondered if I could share the source. Her husband is in the midst of building built-ins and she loves the look. Imagine the red lacquered secretary above without the wire grille - it wouldn't be the same. My shelves came with the grille but after a bit of searching I found an excellent This Old House article full of resources. (image above via House Beautiful here, designer Christopher Maya, photographer not known)
One of the sources mentioned is a company called Rockler. They have two types available, pre-woven wire grill and hand woven grille, in different patterns and finishes.

The This Old House article has a complete buying guide with links for all the screens shown above, including some great patterned metal ones. Love the chain link (C) and mosaic (D) screening. Some of these screens come in 6' and 10' foot lengths and could be used for screens, room dividers or as an interesting window treatment or focal point behind a bureau.
My shelves, before their relocation.
A cabinet from Matthews House & Garden, with a chicken wire grille.