I've been using a mouse mat with a gel wrist rest for many years, but they get dirty and eventually the gel leaks out and they need replacing. And they're not cheap!
So I tried printing my own, and it works! Great surface for the mouse, and good comfortable wrist support.
This really only works with TPU, and it took me many attempts to get the infill right for the wrist rest. I've included the Cura profile, will give you a good starting point.
And I've included the Fusion 360 design file so you can customize to suit your needs.
Any colour you like
I used Cura's Gyroid infill pattern, works well for me at 10% but you'll want to play with different patterns and percentage to get the right feel for you.
My Cura profile is included...