I always used the chewing method. For my last few, I requested an extra long mold that goes as deep as possible. Some may find that uncomfortable or problematic of you have issues with occlusion, but for me, it created a nice comfortable snug fit and higher gain as I also never used a vent.
I did most myself using Lloyd Hearing Aids where they send you the kit, you make the impression, send it back, and then they ship you the complete product. With each kit you get two per ear so you have two chances to get a good impression should one not be as well done as the other.
It isn’t that difficult and generally less expensive then what an Audi charges. They can do both hard and soft molds. I’m not affiliated with them just very happy with their services.