The winglets are also not just a plain old fold but angled inward.
This is also a matter of experience. I have never measured this but I guess X° is no more than 1 or 2 degrees.
Believe it or don’t; but this does make a difference!
Do not tape the fuselage together; just let it assume a natural angle with no preload.
This will enable the gullwing form during flight. It flies much better without tape!
But if you want to try it with tape – go ahead and you will see my point.