Funny you should ask ... I have a helm seat that I don't always use on my Starwind 27! I'm not really inclined to give it up, but if the offer was high enough ....
Seriously, if you need a mold to make one I can probably help out. Where are you located?
I made a flat seat to replace the humped seat because there are many times I want it flat and I find it (the humped seat) uncomfortable even though the elevation is nice when motoring. I use a cushion when I want to sit higher. I did use the humped seat all last year, though.