I want to change my 3rd brakelight plastic cover with a sturdier glass lens, so I need to find a red tint for it, does anyone know where I could get a sample or a small 3x9 inch piece of dark red tint? Im not sure what shades are out there, but I want it to match the colour of the brake lights.

why not just use a red bulb? cheaper, easier

I removed the bulbs and the original plastic to put white LEDs with a red plexiglass cover. The plexi is too thin and does not screw down securely enough to make the seal watertight. I am getting a 1/4 inch glass plate cut and drilled and I want to tint it so that the light will be red. I could use red LEDs, but I want to have the red glass look to hide the insides of the light socket a little more and to match the tails.

go to a camera store or a supplier and ask for a red lense filter...it is what i used on all my interior lights