Download of ChemDoodle3D 2.0.0 for Mac was available from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. We recommend checking the downloaded files with any free antivirus. This Mac application was originally produced by iChemLabs, LLC. ChemDoodle3D for Mac is included in Design & Photo Tools.
From the developer:
ChemDoodle3D is a chemical drawing software. ChemDoodle 3D contains literally thousands of features for working with scientific graphics. It contains many rendering options for atoms and bonds, including size and bond order. Ball and Stick, vdW, stick, wireframe, and line representations are predefined. Easily pick atoms, bonds, and molecules from your scene.
You may want to check out more software for Mac, such as ImageVis3D, Trapcode Echospace or ImageModeler, which might be related to ChemDoodle3D.