Time to start on all the angle that the upper plenum will screw into.

I used .063 x 5/8 x 5/8 along the rear.

I drilled #40 holes and sliced it with the band saw to contour it to the curved shape of the upper egde.

I then used .032 stiffener along the edges since it was easier to open up the angle to match the intersection of the fiberglass mold.

I then used .068 x 1/2 x 1/2 on the forward center section. Again I drilled and sliced to make the bends.

This allowed a perfect contour along this curvey egde.

I then used these cool little 470-3-4 rivets that are not used anywhere on my RV at this point.  Notice I used 3 flush heads where the

two layers overlap.

I then laid up a single layer of 10oz. fiberglass cloth on the inside of my upper cowling.  This photo was taken after hardening had taken place and

I had removed my layer.  I had used Glad plastic to prevent the layer from sticking however it had stuck to the glass pretty good and I couldnt get

it all off.  No big deal Im going to put down a layer of clear packing tape to used as a release layer when I lay up the actual part later so it will be fine.

As you can see it will make a very nice shaped part and maximized the space so that the plenum is as big as it can possibly be to allow

good air flow inside the baffling cavity.