Yes, STERN and CGC. As I remember CGC made playfields also for STERN in the past but with "MMr" and all this remakes they are a competitor to STERN. So very clever from Stern to make the playfields by him self. If with success .... ??!!
I am disappointed from Stern and JJP. So my last NIB games were TBL and Alien. Both machines are fitted with playfields from Mirco and I have no problems so far on this 2 titles. With repro playfields I had also issues in the past. From Mirco and also from CPR. Therefor I avoid buying them but sometimes .. there is no other choice.
So take a million dollars and start your new playfield business ....
I dont understand what is so extremly demanding coating playfields. Maybe in the old days the clear was better due to chemical dilution , in this days in Europe only waterbase coats allowed and also, most producer do not work with a primer like in the old days. (This was why the inserts were milky, not clear as now).
So to produce masses of playfields you need experience. I saw on videos that Stern playfields the inserts are glued in by humans, Mirco Playfields uses a roboter as far as I know. maybe the human is n advance at least in this case.
I had also playfields from BuT Hamburg (BoP, T2), his clear is very good and I had no problems with it so far.