Start out by making a centerline drawing about 1/2" long load the foam into the cutter and cut a 1/2"
line at the center of your foam. I then put a mark on the PP at the the spot the centerline where the foam returns to normal. Attached files

 

Then i draw the topside graphics first and print them using the centerline mark and centerline cut to line the foam up

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Once the topside graphics are done i draw a box around the safe area giving it a face to nest all the parts in.

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I then flip all along the green axis.

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then I add the graphics for the opposite side and print them using my center mark on the foam and the PP to line it all up

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results seem very close *** Note, i did not finish the sharpie on the backside because that green foam is the worst crap in the world and knew it would never fly.

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Top of wing turned out nice even for that green crap foam

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cut one out of cellfoam today, still have a couple little lines to tweak and clean up. I think it came out pretty nice.
Forgot to flip the lettering for the offside Attached files

 

Doh, looking at the pics i just noticed I have the graphics flipped on the main wing