yes it's true I'm going to go on bi-axial fiberglass, to increase thickness and lower the cost a little ...

Yes, you could also use a woven e-glass fabric

You wouldn't get quite the same stiffness and strength from it, at a comparable weight, but if strength is needed you could always compromise on weight by adding a bit more of it than you would carbon fabric

thank you for all this precious information, I'm going to start from the top ;-) Besides, having no weight problem, can I put glass fabrics inside instead of carbon?

The 210g surface layer backed up with a 650g fabric will deliver a part with just under 1mm thickness and on something with narrow widths and angles like that it would feel quite sturdy.

Add in an additional layer of 300g fabric between those plies and it should feel very strong. If you want to be more certain, you can always add in small additional sections of the 300g fabric where you intend to attach anything. The 650g fabric will feel a little less compliant, so be certain to consolidate it well into the corners using a rounded tool of some description

Thank you, in one piece it is not possible? several layers yes, symmetrical yes, but how many? and what type?

If you want a strong door, I would make in one piece with plenty of fiber overlap where direction changes.  I would also used a balanced and symmetric layup.  The 3D core will not make those tight bends, and if you force it, you will have paths for race tracking of the epoxy if you do an infusion.   

1 / 210g Plain Weave 3k Carbon Fiber (1st layer)

2 / 300g / - 45 Biaxial 3k Carbon Fiber?
3 / 3mm 3D CORE PET 100 Foam
4/ 650g 2x2 Twill 12k Carbon Fibre ?
5 / 375g 5HS 6k Carbon Fiber?

but with several folds of carbon fabrics? Shouldn't we see through?