I did think about this a while ago, and it is possible to source EMI shielded custom glass pieces for surprisingly little as long as the quantity is in the triple digits. However, it seems that this would have to be at the top of the product to give a good view (maybe some space on a full-size enclosure on the front panel), which would probably get broken very easily when stacking units on top of each other. At the moment, dropping the cases just dents the corners a little, but doesn't render the units inoperable.
For the time being, it doesn't seem like a great idea to devote time to, but perhaps in the future, with a new enclosure style, it might be worth looking into again. At the moment, I'm just trying to concentrate on the electronics and keep the enclosure design relatively simple. For a 'high end' type of product it's probably a very good idea with a few strategically placed LEDs, but I'm not selling things for four figures (yet).