Apple Motion 3 - Manual (Page 751)

Chapter 8 Working with Particles 751
You can copy particle presets you create from this location to give to other Motion
users, or you can place particle presets that are given to you in this same folder.
Whenever you copy a particle preset file, you should make sure that you also copy any
graphics or movie files that it uses as well.
For more information on saving custom objects to the Library, see “ Adding Your Own
Content to the Library ” on page 232.