So we need a DC motor small, but with a gearbox with enough torque to be able to push the piston and the paste. In my case I've bought a gears kit with all sets of sizes and shapes so is easier to select the size I need and it costs just one dollar or so. I will use these ones connected the motor to the screw. And for the screw I’ve just cut a part of around 10cm from a long M3 threaded rod. We also need brass insertions with the same inner diameter of 3mm. And to close the case we will need 4 x M3 screws and on side of that, we need some small bearings. That's all for the mechanical part.
For the electronics I will use an Arduino pro mini because is small and as the H bridge I have a module with the MX1508 driver. This is capable of controlling two motors but I will only use one channel. We need and H bridge because the motor will rotate in both directions. For the battery I will use the typical 18650 and I’ve also ordered a socket so we can place the battery and easily take it out for recharge. We also need some push buttons and some prototyping PCB, wires and small connectors to make all the connections. To show the modes, I will use a small OLED screen and that's it. This is all we need for this project.