sorry to bring this back, so if the lens is 3 inches or about 76mm, i'm guessing the plastic around it should be just a little bigger or a lot? i'm looking at halo LEDs and they come in 80mm and 90mm sizes and i don't wanna order the wrong size since they're not cheap.

 

Taking another look, this time with the camera out, the closest I could get was 78 mm.