Creating a Tar archive file
A .tar file is essentially a wrapper that will contain the elements of your 3D asset. Similar to a .zip or .rar file - they can be created using lots of different software packages.
Select the DAE file in your file browser and (if using 7zip) right-click and add it to archive. You can download 7Zip here, its free.
This will open 7zip file managers add to archive window – select the archive format to TAR and click OK.
Next, open up the TAR archive and drag and drop in the texture files applied to any meshes exported – in this case there are 3 files; mole_diffuse, mole_normal and mole_specular. The environment texture also seen in this folder was not applied to any export object and therefore is not referenced inside the DAE file & so doesn't need to go into the tar archive.
Create a thumbnail for your Overlay. It can be any 256x256 pixel PNG image however for 3D Overlays it is recommended a simple render of the asset is used.
Add the thumbnail to the tar archive and you are ready to upload to the Studio.
Finally upload the tar file to the Studio & test it out on your device.