The plate needs to fit the case, the USB connector on the PCB needs to fit in the hole in the case (or use a separate PCB with an internal wire for the USB) and the case needs to not have mounting posts where there are switch contacts on the PCB.
The traditional DIY build was "Poker compatible" where the PCB screws to the bottom of the case and the plate screws in on the sides - mixing parts with this is common.
If you have something in mind post links and hopefully someone will know if it's compatible