This is a dedicated wrist support (palm rest) for the Logitech G915 Lightspeed keyboard (full version, not the TKL version). 

The wrist support is broken into 2 parts, which can be easily glued together. 

Printing guidelines:

• Layer height: My version shown in the pictures is printed with a large layer height at 0.3mm for faster print speed. However, if you want a nicer looking print, go with 0.2mm or lower. My plan is to put vinyl on top of it, so top surface finish was not a priority for me.
• Top/bottom: I strongly suggest going with 4 layers for top and bottom each. This will strenghten the wrist support considerably.
• Infill: I chose 15% gyroid, which is fine for this. The walls and the extra top layers ensures a pretty sturdy endurance. I've tested my print with up to 20 kg, and it holds fine. My arms aren't heavier than that, but if you're The Incredible Hulk, feel free to go with 25-30% infill. 
• Material: I use black premium PLA, but I bet this print will look much nicer in a carbon filament. 

Width: ~46cm (full width for Logitech G915 Lightspeed)

Depth: 5.5cm (feel free to scale in this dimension for a more pronounced or less deep wrist rest)

Height: 0.8cm (matches the Logitech G915 at all tilt angles)

Recommendation: Consider using anti-skid tape underneath this part.