Images
All images below are released under Creative Commons CC-BY license, meaning that you may use and/or adapt them for whatever purpose (e.g. to include in your slides) as long as you provide attribution.
For more nice pictures of random geometries have a look at the homepages of:
3D models
Some 3D models of random geometries are available on Sketchfab.
Videos
See more videos on my Youtube channel.