I am not a professional in this domain, so I can't fully help you. However, I know that many experts or companies that work with selling and reselling guns are happy to help interested people like you. I think you should focus on them and see what their advice is. When I started, I was a massive fan of https://3dgunbuilder.com/polymer-80/glock-19-complete-slide-kit/, and I still am. However, I no longer have time for this hobby, so I decided to let it go for a little bit. However, I can't wait to go back to it.