If you want to bring custom 3D models into Cesium then you might be interested in a new plugin for exporting models into the 3D Tiles format.
Publish 3D Tiles from SketchUp with the new Cesium ion Extension | cesium.com
We are happy to announce the launch of the Cesium ion SketchUp extension for publishing SketchUp models as 3D Tiles to your Cesium ion account for use in Ces...
