There a countless 3D files already created and ready to print. Thingiverse is a great source for free files.
If you want to create something from scratch, there are many free CAD (Computer-assisted design) programs available. If you are new to designing in 3D, we highly recommend Tinkercad.
Tinkercad is a free, online 3D modeling program. There are tutorials available on the Tinkercad site to get you started.
Here are some excellent additional tutorials from PromoAmbitions.
Tinkercad Tutorial Part 1 - (Interface and Movement) - https://youtu.be/2JFxtUIOnEI
Tinkercad Tutorial Part 2 - (Shape Manipulation and Scaling) - https://youtu.be/Xy6EuqocJKI
Tinkercad Tutorial Part 3 - (Group, Hole, Align, and Flip Tool) - https://youtu.be/hbQww7pWGt4
Tinkercad Tutorial Part 4 - (Workplane, Ruler, Blocks and Bricks) - https://youtu.be/aa2uboMStVQ
Tinkercad Tutorial Part 5 - (Circular Patterns and Slicing) - https://youtu.be/J_M8LGsElJs
Tinkercad Tutorial Part 6 - (Import Export and Collaborating) - https://youtu.be/1sVJZE2oVHs
