There are lots of expensive Solder Paste Dispenser options but there will come a time that you just need to do more than is practical to do with a syringe and your fingers. That is when building a quick and dirty machine would come in. Good thing there is a system that you can model your endeavors after. The tricorderproject.org has a nice and simple DIY Solder Paste Dispenser project that might be just what you are looking for.
“The prototype that I put together is more of a sketch in hardware to help me appreciate the issues of paste extrusion, and help hammer out a design. Instead of using a plunger, I’ve used a very long lead screw that acts as the plunger, and has a gear atop with a captive nut to transfer force. The gear is driven by a Parallax continuous rotation servo, which I thought I’d try given that it simplifies the design by having an integrated gear box (which gives it lots of torque), and it can be directly driven by a microcontroller rather than requiring a separate stepper driver.”