you can right click or if you want. thanks for asking first thats always appreciated
okay technical stuff,
transparency: I find with scale models, if light shines through the styrene then its probably not in scale brightness wise. I used potentiometers to vary the brightness of the leds and bring that brightness down to a level which would be considered "in scale". I.e if you was small enough to fit inside the model, the lighting wouldn't blind you.
that said, for areas such as the engines, i used cut up heat shrink to block the light and direct it more into the exhaust cans.
but yes, you can lay down a thin primer coat on the inside of the model parts and paint it, gloss black is best for light blocking.
as for the red optics, i just used a red led.
thing is with fiber optics, what ever color you shine down one end, that color will come out the other end. use a red led, get red light out the end, use blue, get blue, and it goes on with green, yellow, pink what ever really.
I used 2 sizes of fiber optics, 0.25mm and 0.5mm. i used a 0.30mm and 0.55mm drill bits along with a pin vice or small twist drill (the kind you turn with your fingers) (several by the end because they snap easily) I will need to use epoxy to fix the optics in place though.
if your new to fiber optics, I would suggest using 3mm leds and get some metal tube that fits snuggly over the led.
add the resistor to the led leg, and wires, use heatshrink on the legs.
put the led in the tube (cut down to 25mm in length) and put some larger heat shrink over the tube and led to hold them in place.
then put the optics in the open end of the tube and use epoxy to secure them in place.
reason is that if your not used to optics and heat shrink, then its easy to apply to much heat to the shrink around the optics and melt the strands. the above method is the safest way if your new to it all.
but dont let that put you off. fiber optics are SO MUCH FUN! and in all honesty, ALOT cleaner than leds alone.
if you need anything else, feel free to ask.