Hi,

I'm not seeing any reason this couldn't be done using the exact techniques covered in the EC video? Have you watched the full series on making a bonnet? 

> Is there a good strong way of bonding two carbon parts together?

Peel ply the glue area, remove peel ply prior to bonding and then apply thickened resin. Or one of the specially-made epoxy or polyurethane glues available from EC.

> do away with a separate inner structure and just try to add extra layers into the outer skin in order to put the strength back in.

You could make the whole outer structure thicker with a sandwich core. This is cheaper and more lightweight than adding several more layers of carbon to produce the required stability.

The inner structure looks pretty simple, you could cut and sand a few strips of foam material, glue those to the top structure and cover them with two layers or so of carbon. There seems to be plenty of unoccupied area so you can apply several of these foam strips + carbon in different locations which would make the hood very stiff. Cheaper and faster than moulding the whole inner area, at least for a small number of parts.

If you want to make the inner part separately for whatever reason, you can use the outer layer as a template. Apply some adhesive tape or plastic sheet as a release and then build the inner structure on top of that. When everything has cured separate the two and glue it together.

You see there are several ways to do this.

Are you talking the area where the outer skin if folded over the inner to lock them together? If so. you wont actually build your carbon part in this same fashion. You'll mold it just like the EC videos. The flange you make around the bonnet or engine cover in your case for the first have of the molding will look like the outer shell. When you go to mold the inner, that part of the mold will copy this folded over part. Then you bond the 2 halves together after making them out of carbon. Sand any excess resin or bonding agent away at the seam. For extra UV protection I would use auto clear on it spraying the outer and inner. When you sand and polish after that, the seam will be hidden and it will look as if the outer layer if folded over the inner just like the original part. 

I agree with the above, would try a cored skin of say 4 layers of cabon, with a nomex core sandwiched between.