Here is what I decided on for button placement, and the corresponding keyboard mapping (if applicable, depends on game) --
This guide has the keys connected to a PS3 controller board, thus the PC will see your device as an actual PS3 controller. You can further customize your experience by using utilities listed below. This allows the device to output keyboard signals when buttons are pressed (if desired). One of the reasons you might want to do this is to prevent buggy behavior when using a Mouse alongside the controller; games will often flicker button prompts or have a jittery camera unless you map the buttons to keyboard keys. There has already been a lot of discussion about this problem in recent years so hopefully the gaming industry evolves to support more controller setups.
ReWASD (Paid application)
Video on how video game controllers work. Really interesting stuff which talks about everything inside the controller, can help you understand hacking them too.
Here's some build pictures from the community. Share yours via the Discord group or through email in the page footer!
First, of course, the obligatory OG Tech Yesterday build:
Dubiello:
AORai:
(custom design)
302Millerz:
(In progress)
and of course mine:
Sherbert ergonomic gaming keypad - uses a Teensy LC and nintendo switch joystick (printables page here)
Azeron Keypad - buy one or build your own