Philipp von Preuschen

The easiest way would be to rotate the bricks into each of the desired rotations and merge them all together.
So you have each brick like four times(each possible rotation).
Another method would be: assign a random integer (eg.: RandInt) to each point.
Set the normal for each value of RandInt with a normal node. And something like this in the group field:
Cheers
CYTE

I wouldn`t say your modelling is wrong. That is not the case. You can model like you did with no problem. The question is always, what is your 3d model needed for? If you plan to stay in Houdini and render your keyboard there, as it is, your approach is absolutely fine. When you plan to deform your keyboard, for instance, as you want it to bend like rubber, your geometry will cause problems. If you plan to export it to a game engine, your fine bevels are a waste of polygons.
In general, when people speak of correct modelling, they refer to subdivision modelling. A style of modeling where you create your object with the least amount of polygons as possible, and the ability to subdivide without problems. To test, you can add a subdivision SOP to your model and see what happens. Pure Subd Modelling also only allows quad and tri polygons.

Cheers
CYTE

If you need them in the viewport together, you can template flag the one and display flag the other.

Cheers
CYTE