I presume you cut out the wheel wells with a boolean operation?

Next time do the boolean on a COPY of the part and "tool" and reverse the boolean (experument - B-A, A-B)...

The same way you "cut" the hole out, you can cut everything BUT the "doors".

You also COULD have used shape merge to "imprint" the gear doors on the boom mesh and from there it's a matter of detaching the "door" polygons, cloning them and using the clones to "intrude"  to form the wheel wells, and by flipping the door polygon clone, the "inside"  of the doors.

Tried texturing and although its slightly off Ive managed to line it up for the best part. First time so it feels good!

Yet another question, how do I begin on the interior model?



I know that if I use extract im going to mess it up. But I have no idea how to even shape the cabin or anything.

Here's a tip.

Instead of using a box to model the wings and tail, try using a cylinder [layed on its side] instead. Flatten it a bit and then move the vertices [while viewing from one side] to make the curvature of the wing.