We use Ender 3 pros and a number of different filament materials because the price of filament is quite low for commercial prototyping we have limited our selves to premium brands in each material for example a 70mm pressure vessel top with stout walls and internal thread to with working pressure 5 BAR required only 40g of nylon so less than £2 with premium nylon filament rather less than a pound in PET-G

The setting you need for threaded holes need some experiment each because it varies each material but we use hole expansion on the cura slicer of 0.1 or 0.2 as a starting point.