I frequently trap off a group of keflings, too. At the moment any kefling that is fully trained in all resources will get sent to my university which is walled in. It seems that if you create an opening and a kefling starts heading towards it, it's a preset movement and he'll phase through walls. What I started doing is opening a wall butt up against the university, so I can place him directly into the university and no keflings can phase through the building to get out.
New GamerTag : MaxSterling