Powerful simulation software packages often produce results that are counter-intuitive. These results are therefore hard to internalize for the target audience who needs to use these results in making nontrivial choices in setting up and managing complex systems with intricate real-time dynamics. We are developing a tangible modeling toolkit to allow novices to set up physical representations of the process that they are interested in modeling and collaboratively interact with it in real time. An initial implementation of this system was used to develop, in collaboration with the United States Postal Service, a simulation tool that allows hands-on manipulation of various operations to help postal managers figure out how to balance work hours to workload and increase throughput of time-sensitive mails.