I am a college student .My club is planning an exhibition on the theme "Topology". Please suggest a main model for the same which is soul for topology. It would be better if it is a working interactive model (hands on) . Please give suggestion. If we couldn't get a good main model then we will have to change the theme to one with a good main model.Here are some other theme we come up with: 1.Tilling and symmetry [Spidron] 2.Graphs & Network [Bridge of konigsberg] 3.Ancient Math 4.Numbers 5.Cryptography Please suggest a theme with a good main model for our expo and some really good model for topology.