Creating a 3D printer file is relatively straightforward. First, you'll need to design the 3D model using computer-assisted design (CAD) software. Popular CAD programs for creating 3D models include Autodesk Fusion 360, Solidworks, and Blender. Once you've completed your design, you can export it as an STL.  This is a 3D printing file format that most 3D printers can read and interpret. Depending on the type of printer you have, you may need to convert the STL file into another format before it's ready for printing—check your printer's manual to find out what formats it accepts. After conversion, you'll be ready to send the model off.