You can take things a step farther in complexity by adding more keys! I decided to build a 21-key keyboard, which isn't too different from the previous example, but offers an opportunity to look at some Fritzing tips as your project becomes more complex.

Here's a look at the Schematic view for the above design:

You'll notice the lack of wires running everywhere. This is because you can use net labels to do the same thing with the GPIO pin connections that we did earlier with the GND symbols. This makes the connections a bit less obvious, so sometimes the practice is frowned upon, but in the case of a lot of nearly identical keyswitches, it's a nice solution to the dreaded "web of wires" problem.

PCB Layout

In the PCB view, you'll lay out the parts and traces just the same as before, only more! Note how both the top and bottom layers are used this time to run the traces without overlapping.

Here's the full Fritzing file for this board:

Here is the set of Gerbers for this design:

Here's a set of the PCBs (note these used a different keyswitch footprint that had extra unnecessary holes that were removed in subsequent versions of the part).

You can order a set directly from this OSH Park link if you like.