Great thread. It's funny - I've been sitting on some pics and my experiences with this for a while. Kept meaning to write it up for the site but haven't gotten to it.
Material: I used a tinted lexan-like material called Makrolon that actually has a hard coating for better UV and scratch resistance. 2 years in, they still look great and feel safer than glass.
I used the old portlights as templates. The Makrolon has a protective film on it. To get the best adhesion, I also used the Sikaflex that requires a primer (209D). So, trimmed off a small frame that I then brushed with primer, primed it, and then applied the compatible Sikaflex caulk (295).
Later, I came back with some Sikaflex 291-White to seal the inside to have a clean finish.
Here are a couple pics...
This is a very easy, low cost project that is well worth it!
- Jeff