I used the stencil method on my 1/9 scale D.VII. Yes, it's a lot of work, but heck, if it were simple, then ARF buyers would be doing it too, right
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You can dowload the patterns from
http://www.aerodromerc.com/ . Click "decals" at the top of the page, and follow the links from there. The patterns are there in .dxf format too, so it is easy to re-size as necessary. Once I had the correct size, I printed the patterns on to the back of that clear film that stationary stores sell to protect book covers, maps, etc. Then I cut out the individual colors, and went at it. The end result is worth the effort!