If your hands are tired rubbing your significant other's sore muscles try this physical therapy tool for soft tissue manipulation. Perfect for force progression for the professional or the amateur and able to be customized to fit your hand for grip in applying either the concave or convex surface.
If you have average sized male hands then you can just print out the stl. If not, adjust in OpenSCAD to fit your hand - export stl and print with your favorite RepRap version.
There is no need to go full fill if you put on a few external layers.
OpenSCAD code by Nick.