I'm a long term user of ArcGIS, and exporting basic extruded 3D models of buildings has always been problematic with this software but it was possible. In my current version (10.3) it seems that it no longer is.
One method is to export to VRML from ArcScene. I have used this feature successfully for several projects the past, but with 10.3 this function crashes with no explanation. This method always struggled with large numbers of polygons, but now it crashes even using a single polygon. My colleague has tried this using a different computer setup with the same result, so I don't believe it's my hardware.
Another approach is to use the 3D analyst tools. I was optimistic that the multipatch to collada tool would be able to export 3D data, but again this tool crashes with no error messages or explanation. There is an existing discussion on this, concluding that the tool only works for 2D polygons-
The whole purpose of multipatches is that they are three dimensional, so if the collada tool only works with 2D polygon data then its pointless. There's no problem exporting 2D polygon data (e.g. CAD export), the problem is exporting 3D polygons.
There's also a "Feature Class Z to ASCII" tool, but it doesn't work for extruded data either.
ESRI can you fix one or more of these tools please? I know CityEngine can do this task, but it should not be necessary to buy this software to perform the most basic of export features