What would you compare a nuclear pore to?

i have to do a project.and i have to compare a cell to a subway restraunt.what would you compare a nuclear pore to?What would you compare a nuclear pore to?
I dont really know a lot about subway restaurants but since the nuclear pores allow the entrance and exit of specific molecules in a highly regulated way (molecules that have specific signals that identify as exiting or entering or both). THey bind to transporter molecules (Exportin/Importin coupled to g proteins called Ran) these serve as the ';key'; that allows them to pass through the nuclear pores (which are huge protein complexes). Now I dont know how to apply that to a subway restaurant but I hope this gives you some ideas.