Which mechanical plotters do you have?
The Makeblock plotter is cheaper, and you have to assemble it yourself. It also has a larger drawing area. The cons are largely that the software that is provided is quite bad, both the firmware on the plotter itself, and the control software.
The Axidraw plotter on the other hand is considerably more professionally put together. Both the available firmware and software is more user friendly. On top of that the overall build quality seems more robust. It is however more expensive, and the drawing area is smaller.
All in all both plotters do what they are meant to do, but the bottom line is that I recommend the Axidraw.
Do you use Processing?
No, nope, nope nope.
The reason for this is mostly that I know Python very well, and that I prefer the syntax of Python over Processing. It is also because the availability of useful libraries seems to be somewhat better in Python.
Recently I started experimenting with Common Lisp. You can read more about that here.
Having said that, I suggest you use whatever tools you find pleasant and understandable to you. Processing, and many other languages/tools, are perfectly suited for doing similar work to what you can see on this site.
Do you share your code?
Almost all my code is on Github. Be warned that the documentation is sometimes quite lacking ...
Do you sell your work?
What background do you have?
I have a Master of Science, specializing in Numerical Mathematics.
How can I learn to do this?
How do you control the plotters?
Most of my algorithms generate vectors on an .obj like format, then I have Python code that interacts with the plotters. Have a look at these two repositories: xy and axidraw-xy. None of them are very well tested, so please be careful.