Making money with a 3D printer in a small scale business is near to impossible. As you will first start your 3d printing basics in which you are going to 3D print similar items as given in the internet the learning process will take its own sweet time and in that duration small things like filament, resin and all will be required and it comes at very good price. Still for running a 3d printing item shops you need to have something new to give people. As already few 3d printing business are already stablished and have there own market so it is difficult to earn money from there.