We have an old paint mixer / shaker at work that stopped working. Several capacitors had blown off the board and several of the time selector buttons are stuck in a closed position.
I made a new board using a piece of HDPE, an Arduino, a solid state relay, and some buttons we had lying around.
There are two buttons on the front of the panel. One is for time selection, pressing it will scroll you through the 4 available mix times: 45, 90, 180, and 360 seconds. The other button simply starts and stops the mixing.