Curtiss OX-5 Rebuild: Changes to Manifold Shell Blank and Tools

Now that I've made 3 shell halves I can see where I need to make some changes to the layout of the blank. I need to have enough steel left along the edges to weld and fold over. I also don't want a lot of extra steel. I marked up a shell with changes to make. The blank under it has the changes.

You can see in the other 2 pictures most of the changes added some steel, especially at the inlets. The inlets all shortened as the steel was stretched because there is no way to hold the end and make it easy to form into a rectangle.
The only area where the edge was reduced was the bottom edge where the forward inlet tube enters the collector. That area wrinkled but never pulled into the form block so I reduced it a little.

I had left an area in the center layer to act as a stop for forming the rectangular inlets. It was beaten back into sawdust so that was just a dumb idea. It might have worked if I had wedged a support block under it, but I doubt it. Because I made the inlets longer, to allow for more shrinkage, I had to cut all that out anyway. I made some blocks from an ash wheelbarrow handle. I rounded the edge where the shape transitions from a rectangle to a circle. There is probably a better shape for this and I'll probably change it when I make a more permanent form block. I made some wedges from plywood to hold them in position.

I had 2 pieces of poplar dowel which I used to form the collector section. They worked fine but were just too soft and were slowly being beaten to death. I cut off a piece of the ash wheelbarrow handle from Lowe's and drew 1" radii in the top corners at each end. They gave me a guide for shaping the edge radius with a plane and the belt sander. The flat back side should make it easier for pounding. With the dowel pieces, the damage was all caused by the mallet. With these blocks, not only is the wood harder but the blows will always be on the back side so the face should last much longer.