In Fixin' FX, people send me their problematic projects and I see where I can help. Sometimes it's a missing instruction from a tutorial, othertimes it's something not working as it should, but in this case, Adobe Community user Stefan Cargoski posted on the forum asking for help. They set up a 3D shape layer and wanted to use Trapcode Particular to trace its outline as it rotated in 3D space.
There's a couple of ways this work, but I ended up showing Stefan the expressions method, as this would also work for CC Particle World. (Don't worry, I explain the simpler method too).
