A generator that outputs one of two values completely at random.

In principle, it's quite simple: In the dispenser there is one item that can be stacked 64 times and one item that cannot be stacked. One of the two is always ejected and so either the upper or the lower Redstone line is activated.

Of course you can build the whole thing several times in a row, so that you have a certain
percentage. This would then look something like this:

Here is a button behind the wall on the left. If you press this button, with a probability of 5:14 a 1 is displayed on the screen and at 3:14 a 2 and at 6:14 a 3.

I prefer this kind of random number generator, because it seems to me personally the clearest and easiest to calculate.

Instructions:

First, build a dispenser and fill it with the following:
1x item that is not stackable
1x item that can be stacked 64 times

Then you build a funnel in front of the opening, which points back to the opening. This way the item goes right back again.
Next, place a comparator on the funnel and an amplifier at a distance of one and three blocks respectively. Then you build another amplifier to the amplifier (which is only 1 block away from the comparator. Finished is the first way.
Behind the other amplifier (which is three blocks away from the comparator) two ways:
-one leads against the side of the second amplifier of the first way
-the second one just leads straight out
Ready is the second way.

If you now activate the dispenser, the above mentioned principle will run.

I think it's all pretty easy to break down.