The Cubik Studio exporter lets you publish 3D files straight from Cubik Studio to Sketchfab.
As of Cubik Studio, the Sketchfab exporter is natively integrated! As long as you have the latest version, you can already export your models directly from Cubik Studio.
When the upload is complete, a popup is shown saying so. Then, you can view your model on Sketchfab, adjust rendering settings, and save the default view.