Both times to replace leaky ports, non-opening. Both times using a smoked acrylic material purchased from a local vendor. Both times the owner's work was succesful, no leaks. Both also had the same issues to deal with. 1. both boats had an outer fiberglass coach roof and an inner fiberglass cabin headliner. The gap between the two had to be addressed and was actually part of the origial reason for the leaking ports. 2. without an actual window frame the inside of the cabin now required fabrication of some sort of trim to cover the raw glass in the opening. that complicated the projects. 3. Both boats look like someone bolted acrylic to the outside of the coach roof. It is neither factory looking or a "finished" look IMHO. Nothing stock looking about it. But that is something they need to be happy with, not me.