I have my own injection molding machine in my garage, DIY all the way. Everything about molding is precise, and it has to be, it’s not nearly as forgiving as FD

I have my own injection molding machine in my garage, DIY all the way. Everything about molding is precise, and it has to be, it’s not nearly as forgiving as FDM printing in terms of failure modes. To achieve what you are describing I have two molds that I rotate in and out of a toaster oven, not kidding. Every thermoplastic pellet has a detailed data sheet on expected temps and the like and mold temp is simply one of those.