I bought two rolls from Maine, gave one to my boss who sails a leaky Cal 27-7 and am about 2/3 through my roll.
Here are pics of my plexiglass replacements. The biggest challenges were getting the old ones off, removing the caulk and glue that stayed behind and then removing duct tape residue. I was getting the plexi for free so I could not complain about the 3 month delay however I had to temporarily (3 months) cover the window openings with plastic held in place with duct tape. During Toronto's hottest summer ever that duct tape, under a green tarp, was baked into the deck. Come late Oct I froze my fingers getting that duct tape residue off with Goo Gone and acetone....but in the end all worked out. I will give the screws another turn or two come warmer weather.
This qualifies for cheap projects as it only cost me the $50+ US into Maine's bank account but I wanted to post it with the butyl tape because it was so easy to work with. I have also used the tape to seal one of my stanchions where a little "side arm" support stuck through the cabin side and I will do two more in the spring.