Each button has an LED and 470 ohm resistor for showing it's been touched. It also has a 10K ohm resistor connected to a via, a connection between the top copper and bottom copper. The copper under each button made in Affinity Designer acts as a touchpad and this is connected by the via to a trace leading to the 10K resistor to the AT42 chip. It appears the touchpad copper is left unconnected as a circuit but, trust me, it works.

ith the art design on front, it wouldn't be  as nice to route copper traces between components on that side. So all traces between components was routed on the bottom copper layer, effectively making the routing only on one side (barring the capacitive touch keys on the front). With two 14 pin chips, that is a mess of connections and very tricky to lay out neatly and effectively.

Tips used to do the layout:

• The LEDs were placed on the outside of the buttons due to ergonomics, so it made sense to route the 10K sense resistors on the interior portion of the board.
• First trick was checking the pinout of the chips. It made the most sense to put one with pin 1 pointing up, and the other rotated 180 degrees with pin 1 facing down (the bottom of the board). This had the most pins routing to the sense resistors and the opposite pins to the LEDs.
• The choice above is NOT 100% ideal as not all pins for a function are limited to one side of the chip.
• The second trick was to route some traces under the some resistors.
• An ideal layout is a clean, orderly one but this is much harder in this complex circuit compared to the NASA badge project which had a very simple circuit.

There are many tutorials for making good cad designs and in using KiCad, so I will not repeat them here.