Seat frames/springs I did a 1950 chevy that had the body channeled over the chassis so much that the seat sat way to high so the only way I could do it was by making plywood base with elastic webbing over holes then soft foam so it still looked fat but the driver and passenger would sink down low when sat in .
I even had to make a loop over the tunnel and fit rose joints to hinge back rest as the original hockey sticks had to be cut off

I did a 1950 chevy that had the body channeled over the chassis so much that the seat sat way to high so the only way I could do it was by making plywood base with elastic webbing over holes then soft foam so it still looked fat but the driver and passenger would sink down low when sat in .
I even had to make a loop over the tunnel and fit rose joints to hinge back rest as the original hockey sticks had to be cut off