Started with the original seat base that came with the airframe. I modified it by fabing anew seat back frame that was about 5” taller than the the original. I also enabled the seat back to be tilted forward with a release latch and pivot points.
Next thing was to cut a base from 1/4” plywood and a back from 1/8” plywood.
I cut 4” high density foam for the base and 2” med density foam for the back.
I got some remnant fabric from a fabric shop for a discounted price and covered the seats.
The fabric was attached with contact cement to the underside of the plywood base and back.
Same process used for the back seat.