Ian, If you can get it, Kydex is a good UTA light shield. If you cannot get that look for some sort of Black stiff plasic, like that you find on plastic folders polypropylene is a good type.. Not the big folders but the small ones. It is still enough to be flexed into the circular shape of your UTA. Put it on the inside of the UTA. You can find these folders at any supermarket in the stationary section
