The main model here is a reverse bowden and cable support bracket, which is needed to make the KP5L capable of printing reliably. The printer as-shipped makes no accommodation for the filament path between the runout sensor and extruder, which leads to frequent print failures. This mod deletes the filament runout sensor, but they're dumb gimmicks anyway. You will need three M3x10mm bolts to mount the bracket, as the existing bolts are too long or short. Print both parts as provided with at least 6 walls and 20% infill.
The bed cable strain relief is not strictly necessary for basic functionality, but it's STRONGLY recommended for safety. Print as provided (yes, really) for maximum strength with normal supports on buildplate.
The 70mm leveling knobs are entirely optional, but who doesn't like a really big knob? They require one M4 nut each.
I managed to get Klipper installed on my KP5L, and it works well. Just follow these instructions for the KP3S, but use my config file (rename the to printer.cfg) and use the compile settings included in it. https://3dprintbeginner.com/how-to-install-klipper-on-kingroon-kp3s/
I've also included start and end GCODE and screenshots of the Cura printer profile I created from scratch, since the manufacturer doesn't provide one.
Original factory firmware, in case you fuck something up and need to revert back to the original condition: https://archive.org/details/kp-5-l-original-factory-fw
The PTFE fitting was borrowed from spool2kool on thingiverse: https://www.thingiverse.com/thing:3374447
My full review of the Kingroon KP5L: https://www.youtube.com/watch?v=0-HNlwXncwo