If you can not fine what you are looking for. you might take a look at what Tec-Plastic stores have.
Your lights look like they are recessed so all you would need to do is take along some measurements and get a piece of plastic and make a frame for it and you have it made.
You have a good situation because your lights are recessed.
If your not to handy with wood you could check with a carpenter about it and I am sure he would not charge too much as long as you paid for all of the material.
Just a thought.