A functioning scale model? One that has a propulsion system, a rudder, etc., and can be sailed around a pond? That would really be something.
One issue is that just scaling the model by a factor of all the original Titanic's dimensions won't result in a model that behaves comparably to the original Titanic. To do that, you'd need to scale it to maintain the same Froude number - which is a ratio of the flow forces to gravity forces. If, for example, you scaled down a 17' canoe to, say, 0.17', it wouldn't float at all like the full size canoe, more like a fishing bobber, and would probably be a disappointment.