Final revision for Simple Pusher Paste Dispenser.

It now uses NEMA17 stepper motor and 10 cc cylinder.
The video demo is https://www.youtube.com/watch?v=FvaFZ5cur7Q
There're multiple issues:

1. Paste continues to flow after the motor stopped moving. It seems that the syringe expands slightly under the paste pressure and then elastic deformation forces keep pushing the paste out of the needle.

2. Stepper motor has no way to fill the pressure (and force sensors are generally larger than it could be fit in the syringe), so there's no way to know when to stop. If stepper motor continues its rotation, at some point the back pressure becomes high enough to cause skipping steps.

3. NEMA17 stepper is heavy.