I dont know if someone has made somethin like this, but i hope i made my gamepad hack this way and somebody else find it interesting to use.
I see a lot of people doing nice and clean work with the cables, all tied togethers in groups, following clear paths and so (they usually go for i-pac or similar) but when comes to gamepad hacks is usually a pcb just sitting there at the bottom of the control's box. What i have in mind is doing something like a "box" for the hack, so is secured and protected from accidental ripping and is easy to (for example) move to another place like if you decide to make a full cabinet, just unscrew the cables and are ready to go.
This is the "lower plate"
Is a 3mm MDF, the boxes on each corner are wooden blocks with pre-drilled holes for screws.

This is the "top plate"
Also 3mm mdf, is for covering the PCB and the wires, has a cut for easy acces to the output cables and is secured with screws to the bottom plate. Has a "label" just to make it look more "professional" (and is a good reminder too)

The top and bottom screwed together

The PCB in the firs image is held in place with those black boxes you see around it, who actually looks like this:

The lower plate may include a couple of "flaps" to the sides to secure the "box" to the CP using screws.
Just an idea
Thanks for reading