Playseat shakers for sim racing

Following the installation of the rumble motors for the Fanatec CSL pedals https://www.thingiverse.com/thing:3089816 , I realized the Adafruit motor shield had still 2 free connections for additional motors.
Salvaging a couple of OD 29-30mm DC motors (i think the donor was a printer) I built a "poor man" shakers.
I am very pleased with the result, it add a feeling when going over the track's curbs and bumps.
The electronics consists in an Arduino Uno + Adafruit motor shield V02 meanwhile the