colored epoxy
 

If you are assemblying a arf and it is already covered mix up your choice of epoxy and add about 1 or 2 drops of the particular color that your plane is. white, black any color. I use the small pactra 1/2 oz model paint. mix it up and waa laa it looks great. when you wipe up the excess you have just made a color matched filet . I have even mixed colors to get the right match. I also might add that I have never had a glue failure. Try it it really works!

colored epoxy
 

Thanks 4 the tip av8r4aa.
Got to try that. :D