We have 12 free PowerPoint backgrounds to download here, all with a 3D feel. We've bundled them up so that the backgrounds are already inserted into the PowerPOoint presentations, so all you have to do is download them to your computer. You can then amend them to your own needs and not have to bother about inserting those backgrounds into PowerPoint yourself.
If you see a background you like, click on its image above and it will open up in PowerPoint. Because you are opening files from the internet and the internet is an untrusted source, you will see "[Read-Only]" in the title of the template. Once you save the template to your PC, however, that's as good as telling PowerPoint you trust the template and the warning disappears.
We tend to produce a mixture of 3D backgrounds and 2D backgrounds too, so stay tuned for those.