Have had a rethink about the seat. Needed to check it with rads… because I really want to find an upholsterer that can get clear rads as close to the 5mm used on the CAD model. I also placed the central line in the model to check that. Actually does a lot to reduce the bulk and break up the top surface.

Think I’m relatively happy to send this off to the upholster I found.

Have been thinking about making an expanding PU foam base to ensure the mold is accurate. Could make a 3D printed mold to do this. Wondering if I need to make a harder foam substrate and how hard this PU foam stuff would be? So many questions.