Worth noting that modern pistons have ovality!

See:

https://en.wikipedia.org/wiki/Piston

And a this one I found via DuckDuckGo

https://blog.wiseco.com/pistons-arent-round-profile-and-oval...

Interesting! My statement was based on what I read in the Museum of Retro Tech:

http://www.douglas-self.com/MUSEUM/museum.htm

Many designs have been tried over the years, but suffer from oil leaks, low compression or high manufacturing costs.

Something I've discovered by accident is that the lathe sits idle in most machine shops these days. If you can design something that can be made on the lathe, you can often get it done with virtually no waiting time.