so you need 1 of 5 outputs to come on, then second, the third etc. then clear, then to start again, but with the 4th then the 2nd then the 5th etc
so how about a clock running at a very high speed, connecting to a 4017 or some other counter, . you then need to stop the clock at varying times, to get a different number of outputs and hold it in a latch.
now if the display was powered from a dropping resistor, which generates heat, then a ptc or some other heat sensitive device would give a varying resistance....... you can also add a light sensing device, or any other components that will give a slight variation in resitance (or capacitance, or inductane, or voltage etc)
if the clock's running at 1MHz, then you won't need much of a percentage variation.
if you manage to get some variation into the high speed clock as well as the slow one, then it's even more randomised.
infcat your trying to design an unrelaibel circuit. which we all know is incredibly easy to do. inadvertantly