I learned/did something new today, so have to share.
I'm putting the windows in the Indy One from a 4x8 sheet of clear PET.
I tried to tint the windows using $50 of tint film, it just doesn't work on plastic.
The solution? Dye! You can dye plastic using fabric dye. It works quite well, the windows are now a nice dark tint, and was only $4, plus $6 for some dollar store aluminum baking pans I taped together and used plastic sheet to make a waterproof 5ft trough to soak the side windows in the dye solution.