I made a custom wood and leather wrist rest for exactly this. It’s fairly tall and has a soft curve at the corner opposite the keyboard. The heel of my hand rests on the curve. Watchband touches nothing. I modeled it after the keyb and wrist rest on an X220 and its predecessors. Going on at least 15 pain-free years post blowout.
- found a stick of pine that was the right thickness (3/4")
- cut off a chunk a bit wider than the alpha keys (~12")
- measured the distance from the keys to the edge of the X220 wrist rest (3")
- took off 1/8" for border of the keyboard frame, ymmv
- approximated the curve with a rasp and sandpaper
- after a week or so, Elmer's glued a sheet of soft leather over the whole thing
My current keyboard is a Filco Majestouch 2, but I originally made it for a cheaper Magicforce, very similar geometry. It's too tall for the NuPhy Air60. I'd say the thickness works out fine when the top of the wrist rest is about 1/8" above the bottom of the first row of keys.
Padding isn't really necessary. Laptops don't have it, and there are plenty of wooden wrist rests out there. It's the geometry that matters. That said, soft leather is nice. Neoprene could work, but it gets gross.
