For many of the touring uses on this site, you'll have to get your 3D model in the .DAE format. This is a pretty straightforward process:
1. Save the model as a KMZ - From Google Earth, right click and choose 'Save Place As' and choose KMZ
2. Change the extension from KMZ to ZIP - In your Windows or MAC explorer window. Accept any errors or warnings.
3. Unzip the KMZ - Using an unzipping software, unzip or extract the zipped file.
4. Open the 'files' folder - look for the file with the .DAE extension. It is usually named the same as the KMZ file name. You can move that out for the zipped folder to anywhere on your computer.
5. Profit