The driving gear for a massage of fingers was constructed and tested. We choose 5-bar linkage with 2 servos. Here is the assembled construction and components. The lever arms and bases are made from FR4 Blank Clad Circuit Board using micromiller, or it can be 3D-printed.
We made model linkage to calculate the angle values. We use simple test program to controle servos by potentiometers to find the angles for movement.