I forgot to describe the z-axis. Not quite such a bargain as the XY table as it does not include a stepper motor, limit switches or electronics but I am pleased with it all the same. It is very solid so I should be able to mount any type of head I want on it.
It has a mount for a Nema frame motor. I have a few of these lying around but unfortunately the shaft exits from the wrong end so I will have to mount one on pillars.
These are 1.8 degree step motors so with half stepping I will get 400 steps per rev. Each rev of the leadscrew moves the carriage 20 mm so I will get a resolution of 0.05 mm. It doesn't need to move very fast so I will try to get away with a simple constant voltage unipolar drive circuit.