@uplinker...IIRC he was a postman....now a full-time Engineer building models which sell for the appropriate price and he has a waiting-list so can afford to take commissions that interest
him Even made the moulds for his own exact scale tyres!
@ R Petersson...Sorry, my apologies...you are indeed taking on a real challenge.
I would work on the principle that if it wasn't cost-effective, the full-size builders would not put them in!
As the size goes down, the scale of your losses and juggling clearances/thermal distortion and expansion/balancing....just grow!
Good luck with this enterprise and I hope you keep us posted.