This is a model I've designed to help me align my printer bed on my Neptune 4, it should work on the Neptune 4 Pro as well, and possibly other printers, but I haven't tested it. 

To install it just unscrew the two screws that hold the cable bracket in place, remove the bracket, and install this one in its place.

You may need to loosen the screws and adjust it slightly before tightening again to make it square with the printer bed, as otherwise the bed may be misaligned when installed.

It doesn't need any additional hardware, but I recommend printing it with a high temperature filament if you intend to set the bed to above PLA softening temperatures.

The best settings I found to print it on was 15% infill with 2 wall loops on standard quality. The model doesn't need supports, or adhesion on the textured PEI plate.