If you would like to create your own design:
Buckham Library suggests TinkerCAD as a beginner-friendly software for creating 3D models. It's a free 3D design software that runs right from your browser. Simply drag and drop shapes to design anything you can imagine. Get started here!
If you need a program that's a little more complex and capable, try Blender (free) or Fusion360 (free for hobbyists).