As of Modo 11.2, the Sketchfab exporter is natively integrated! As long as you have the latest version, you can already export your models directly from Modo.
If you're using Modo 11.0 or 11.1, download the Modo 11 version from this page.
If you're using an older version of Modo, downloaded the Modo 601 — 10 version from this page, or from the My Products page of your Foundry user account, under Modo Sketchfab Kit. It installs both Sketchfab V1.1 for Modo 601-10.0, and Sketchfab V2 for 10.1 onwards.
Before installing this LPK, any previously installed versions of Sketchfab must be uninstalled by deleting the Sketchfab folder(s). Sketchfab folders may be found in Content/Kits folder (accessible in Modo by going to System → Open Content Folder), or the Configs folder (accessible in Modo by going to System → Open User Configs).
Uninstall any existing version of the Modo exporter.
Download and open the LPK file.
Modo should show a successful install message and ask you to restart.
The plugin should now be available in the toolbar above the viewport.
How to use
In the toolbar, click the Sketchfab button.
Click Log in and follow the prompts to authenticate your Sketchfab account.
Enter a title, description, tags and mark it as
Draft if necessary.
User Current FBX options will apply your export settings rather than the default FBX settings.
Export Animation will include animations in the FBX.
Auto Freeze will freeze/apply any transformations in the scene.
The entire scene and all layers should be exported. When the upload is complete, you can view your model on Sketchfab, adjust rendering settings, and save the default view.
For more detailed instructions and other information, visit the blog or watch the video above.