I made a wrist rest for my mechanical keyboard at work. I didn't want to buy a new wooden one for 20€ or more. I printed mine in PLA with two colors. The openscad file is also available. So you can change the form, lenth and depth as you like.

I provided stl files for 360mm (TKL) and 310mm (should be 75% Keyboards) length. Depth is about 80mm, height is about 16mm (will be more when glueing bumpers to the bottom.)

310mm Wrist:

wrist31l.stl
wrist31r.stl

360mm Wrist:

wrist36l.stl
wrist36r.stl

print wristCon.stl to glue both sides together.

I also added whole sized stl files wrist36complete.stl and wrist31complete.stl.

have fun!!1!