robotic workcell design

I was trying to come up with something interesting to base a few
articles in Servo around. The thing that keeps popping into my head
is a robotic xyz workcell. Most of the construction articles are
about the Nth sumo robot, line follower, etc. etc. A workcell would
be a worthy project that could be followed up with many articles on
things to do with it. Something around 18" x 18" by 6" travel (xyz)

Some of my ideas:

Add machine vision and a vacuum pickup tool to create a pick and
place machine, or even a puzzle solving robot.

Add machine vision and a electro mechanical syringe to create a
solder paste applying machine.

Add sensors to create a 3D digitizing machine.

Add a small sealed CO2 laser to create an engraving machine.


The problem is coming up with a suitable gantry design that can be
built for a price. I would like to have a design that could be built
with minimal hand tools for under $2000.00 using new non-surplus
sources. I have spent a few days looking into the mechanical side of
things and I do not think it can be done at that price. Opinions?