Going back to the inlets today, decided to focus on just the RHS to start with - slightly more space to work with. I cut the baffle floor further back and bent it downwards,
I used a length of 4" pipe which hopefully form the aft ring for the joint. Then strips of .025 AL were drilled and cleco'd to hold the ring in place.
I extracted the parts and re-assembled on the bench. I used some screws to replace the clecos and a backing board to keep in planar.
Then mixed some plaster of paris and started building up the layers.
After the first session had cured a bit, the lower profile was built up. I think it is probably going to be a two piece shape. Tomorrow I'll try shaping it further.
I have no idea if this is going to work for a fibreglass plug - time will tell.
