For the entrepreneur starting out in holster mold making can be challenging……there is a lot of trial and error. If you are using a foam press doing individual project holsters for yourself, there is a lot of online information showing how to do it. It is surprisingly easy to get fairly good results if you are careful and patient and have free time to fine tune your efforts.
Remember though that at times trial and error will seem more like error and error. If you are interested in forming your own molds it can be done! Google search homemade Kydex holster and you will have plenty of resources. Good luck.