I'm looking for different methods to create window "glass" for resin or other customized vehicle bodies.

I know people used to use 35mm camera film cut to shape for tinted windows, but being in the digital age this really isn't the best option. What do you guys recommend?

I know my experience is limited in making curved windows, and my detailing isn't always sharp.
What I use is clear styrene sheet (or I really slum it and use toy packaging plastic but that can be noticeably wavy), cut to shape with lots of test fitting and trimming a little at a time. Here is an example that used simple flat windows.

To install, I put a generous bead of that Micro Kristal Klear (or again, go cheap with Elmer's School Glue, both dry clear) around the window edge. A neat thing about the Kristal Klear is that it smooths over gaps, even creating a window by itself if you spread it across a small opening.
I think I've read people tint it with Testor's Smoke. I have used clear green paint for RC Car bodies, but that etched the plastic. (In the build pictured above, I didn't have an interior, and I painted the tint from the inside, so I didn't let the etching bother me. I can't find a photo of that.)
For odd curves, you probably need to form a master from putty or something very smooth, and vacuum form a curved window over that-- like they do for canopies on the airplane site.
I hope this helped you in your quest. At least that gets a discussion going, and hopefully others will add to that.
-Sean H.

update: The RC Car paint was Pactra brand, and the internet tells me that it's just been discontinued. You didn't want that anyway.

I am not using toy packaging, that stuff scratches way too easy and is a bit flimsy as you say. I'll see if I can source some transparent sheet styrene. The windows are old school, all flat glass, so I can us the window frames to draw some templates and just trim a bit to fit. I'll also need some Micro Kristal Klear. I have a hobby shop here that sells transparent colors for RC cars, Tamiya and a couple of other brands that I think are water based. Thanks for the tips Sean

Not to belabor the point, but I found this photo (this recovery vehicle still needs black tread paint on its upper surfaces and thinner replacement handrails before I'll call it done). You can see that the windows aren't clear.

I've seen your work before, so I trust you'll do well! Take lots of pictures!
-Sean H.

Thanks Sean, and will do! How did you prep the windows before painting the transparent green on them? I'm thinking a mild soap and water bath should do the trick?

Admittedly, I didn't prep them first. Good idea though!
Also, if you do that, clean them off the kit, because I think the Krystal Klear is water-based.
And while I'm at it, disregard my earlier reference to Pactra paint. The photo above shows what I used.

It's all good Sean, I caught that part I just picked up several thicknesses of clear styrene sheets, some tinted Tamiya spray paint, and some other supplies. I won't be able to start anything until next week, but the whole project is an experiment so I will be glad to start a thread for it all here. I'm going to be trying out some new paints and I will be using Alclad II for the first time.

Your local office supplies store should have packs of empty CD covers which are very cheap and come in a variety of colours.

Thanks Damian, I completely forgot about those things! The colors are a bit light, but the thicker acrylic may be useful. I may experiment with that as well.