I looked at memory foam. It compresses too much and recovers too slowly for this application. And the other side effect was how much heat was reflected, my thighs were sweating on drives much more than an hour. That was not expected.
I found a place will sell me orthopedic grade upholstery foam. I also like that it can be cleanly sculpted with a hot knife tool. So, fairly complex shapes or contours are doable at any work surface that has an electrical plug nearby.
My plan is to simplify the sewing process by creating a new three part lower seat cushion consisting of the improved (longer with better thigh support padding) center pan. And then slightly taller and firmer side bolstering attached to the base with their own sheet metal pans to attach the foam and cloth cover to. I can then just use the base to attach the individual parts onto. The original weight sensor can be inserted into the new foam and plugged back in, same as the original. I'm not an upholstery guy. But this doesn't look terribly difficult when I know what I want and can break it down into three separate fabrication tasks. The upholstery guy who looked at the seat and my drawing said it was three easy pieces.
I found a place will sell me orthopedic grade upholstery foam. I also like that it can be cleanly sculpted with a hot knife tool. So, fairly complex shapes or contours are doable at any work surface that has an electrical plug nearby.
My plan is to simplify the sewing process by creating a new three part lower seat cushion consisting of the improved (longer with better thigh support padding) center pan. And then slightly taller and firmer side bolstering attached to the base with their own sheet metal pans to attach the foam and cloth cover to. I can then just use the base to attach the individual parts onto. The original weight sensor can be inserted into the new foam and plugged back in, same as the original. I'm not an upholstery guy. But this doesn't look terribly difficult when I know what I want and can break it down into three separate fabrication tasks. The upholstery guy who looked at the seat and my drawing said it was three easy pieces.