How to fill an invisible shape randomly with objects until the shape is completely filled by them?

[Taskmanager1969]

Hi,

I would like to spawn question marks randomly in an invisible circular shape until the shape is completley filled by the question marks.

Like drawn in the following pictures (Steps are simplified and reduced to only four steps for the explanation. The animation would have one keyframe for each spawning question mark):

 

 Thank you in advance!

 

[Mylenium]

Particle systems and a bit of masking are the answer.

Mylenium