3D models are developed using 3D modeling software. Popular ones include:
The last one is free and open-source, the other two are proprietary. We have used Solidworks to create our models, so the source files are in a proprietary format, which requires you obtain the software. Check if your school, college or university has free licenses for you.
Luckily, you only need the proprietary format if you want to modify the model. From the modeling software, we have exported all our models into a ‘universally printable’ open format called 'STL’. This is the only file you need if you only need to print the model, not to modify it.
Another application, that usually comes with your 3D printer, is called a ‘3D slicer’. It takes a STL file and converts it into a ‘G-code’ file that the 3D printer can read. Usually, you will just send the STL files to your lab technician, or to whomever is knowledgeable about the 3D printer and wait for it to finish printing!
(*) All 3D-print files available through an open-source license