I like the "one side of the light blocker" idea--and instead of painting it, some gold-colored foil might work--could just wrap it instead of paint it.
ETA: just found this
http://www.whimsie.com/aluminum%20foil.html#anchor5508small samples available (would be careful --may not want to have the modeling light on heating this stuff, not sure how the material would respond to heat, as the coating might not survive, or might flame for all I know)
Might try brass foil or thin sheet--actual metal, not a coating. Hmmmm.....