The plastic boxes contain round containers with screw on-lids so nothing can ever spill out. If going to a crop you can just put a few round ones in your purse if you don't want to take them all.
The plastic boxes either have 30 small containers or 18 medium containers (there is also a box with larger round containers).
This will hold 8 of these boxes you have a possibility of 144 medium containers or 240 medum containers. For almsot everything I have the small work fine but I have a combination of both.
I also lay the Cropodile on top of the containers and set the entire carrying case (from Michaels or Joannes or HL) in my craft wagon.
This works absolutely awesome. The flat boxes with the round containers came from Joanns but you can buy them in any hobby store in the bead department.