But now that it's mostly finished, I started on the pan, the actual part which will be padded and sat upon. I started by clamping the hump in place, and making a paper pattern.
I also cut a relief in the middle to clear some of the electronics which are mounted under the seat.
The pattern needed trimming to get close:
Next I transferred the pattern to paper and cut it out:
Notice the electrical tape I placed on the border of the pattern, this extra width will let me fold the pan down to cover the frame and look nicer.
I will cut the relief for the electronics in the metal later.
Kind of looks like a headstone, no?
After some trimming, mocked in place, looks pretty good: