Plastic window on 2001 Boxster
 

Anyone try this sew on, whilst top on car?

Yep. It's certainly doable. It cost like $30 in total and turned out really nice. The downside though, it took forever, and was VERY tedious. But I watched a bunch of youtube videos in the meantime that I wouldn't have had time for otherwise :) When I was at halfway I remember thinking I'm an idiot and asking my wife to punch me in the face if I ever commit to do this again. I think I had a thread about it somewhere here, look it up by my name.

Just "bite the bullet" and install a new top w/the glass back window. Yes it's costly, and yes the rear glass is a bit smaller than the plastic, BUT the glass has heating wires for defrosting and your car already has the plug and panel switch (installed at the factory).

Your top probably has seen better days, since its probably original, making it more than 20 years old.

A new top quality top w/glass will cost about $1500 installed by an experienced installer.

This is my thread on replacing the window... I did three roofs during the summer of 2022. I would not do this with the roof on the car, but removing the roof is easy, half an hour once you figure it out. Helps to have a helper to lift it off after unbolting everything.
https://986forum.com/forums/boxster-general-discussions/82464-diy-rear-window-my-new-top.html

Can do
 

A section of the stitching around my Boxster's window was broken when I bought it. At the time, my wife and I laboriously sewed it back in place with needle and thread. When an adjacent area of stitching failed a few years later, I used a sewing awl to stitch the repair. This method gave superior results and wasn't as difficult to use as well. I found that I it worked best to open the top to service position and disconnect the cables to the back of the top so that the inside as well and the outside of the window could be accessed from the back. Holding a thick piece of Styrofoam against the inside of the window to keep it from moving while inserting the needle from the outside made it possible to get more even stitches. This is by no means easy to do, but a section of broken stitching can indeed be repaired with the top in place.

Some more photos of my project here (near the bottom of the page) - https://rx19jones.wixsite.com/projectboxster/projectboxster4

http://986forum.com/forums/uploads02...1729344338.jpg