Lightly sand the
sheet to remove fuzz. If doublers need to be added before the sides
are built go ahead and add them.
Join the fuselage sides using double-stick Scotch tape. Sand the
sides to an exact match. Take your time aligning the sides so that you
don't remove any more material than necessary.
Note that the right side may be shorter than the left side due to right
thrust. If this is the case with your model then take that into
account when sanding.
As always, remember to build a left and a right side. I find that
placing them next to each other as a mirror image helps prevent building
two of the same side. I am proud to say that this is one of the few mistakes I
have yet to make.