OK, this is way too neat to not highlight here.
This preprint provides a very simple and doable demonstration of quantum conductance in a 2D conductor. In fact, it is so simple that the authors claim that ".. the setup is operated full-time, needs practically no maintenance and is used on different educational levels." Nice!
The paper provides a good basic intro to the issue of conductance, and what happens when you get to the "ballistic regime" of electron transport, i.e. when the length scale is smaller than the mean-free path of the electrons. Any intro QM student would be familiar with the energy level diagram shown in Fig. 1(b). And it really is a neat experiment. You can see the step-like increase in the conductance.
A very good paper, and could be a very good demonstration to add to either a class demo, or a permanent exhibit. Another clear effect of out of quantum mechanics.