I have seat cushions on order from Oregon Aero. The rest of the interior is aluminum that I fabricated. The canopy fairing on mine is the canopy frame (it's not standard at all) and that's painted fiberglass.
Since I have a manual flap handle and a somewhat unusual crotch strap mount, my bottom cushion is somewhat different than others. And apparently my back is sufficiently different that the lumbar support is also different. As a result, there are several iterations of shipment back and forth for trial fits.