Flaps

I have never done anything like that but I would be very careful were you cut. Use the smallest, and sharpest knife you can I guess.Good luck on that one. Maybe if you have access to resin you could mold new copies of the wings (if they arent too big and use the resin copies as the main portions of the wings and then the plastic kit parts for the flaps. That would be feasable I think if again if the wings aren' too big. I wouldn't replicate wings the size of the ones on my Monogram B-29, that would be ludicrous.

I know what you're up against 7474.
I'm in the middle of a Boeing 377 build, 144 scale Minicraft. To give the model a more realistic and relaxed look, I decided to butcher the trailing edges of the wings!
Now I'm in a bit of a jam so I put the thing on hold until I get more creative.
Sorry I'm sbsolutely no help.
Who knows, maybe we'll both get some advice on this thread.

Modern airliners use fowler flaps so, there is WAY more to it than just "dropping"
them. They are multi-part and slide out from the trailing edge of the wing. If you
have the skill and patience to do it, it would look fantastic. Myself, I wouldn't even
think about it.
Ray

7474;
If you want to see some great photos of airplanes of all types and makes. And airplanes of just about every airline in the world then go to airliners.net.
It's got some amazing shots.
jimz66 is correct, the trailing edge devices on the jumbo jet are extermely complex. The 747 in particular has three sections that slide up into the flapwells wiht a complicated carraige system. [:0]
But I digress. Check out the site, you'll love it.