Not sure if this van_dam might work for you. I found it randomly searching through my Unraid server’s App store and it seems to be built around 3D printing files. As a note, I haven’t worked with this one personally yet since I haven’t had the time to get Postgres and Redis set up, but I have this pinned to come back to it. Could be worth a look!
And if you listen at 1.5x speed, does that just burn your 15h faster or can you fit in more time?
It’s an interesting idea, but I think the only way I’d use it is a “try before you buy” and go out to Libro to make the purchase. At least that’s the only way I could realistically see using 15h/month.