Dual linear rails on all axis with dual sliders on each XY rail and one long slider on each Z rail.
Thanks for the comments guys. I have done quite a bit of research on GT belts for another project. This document was really useful.
[attachment 80239 timing_belt_specs.pdf]
I was concerned that a 6mm GT2 belt might flex too much, but at such low power levels I am feeling OK about it. However I will design it to be able to retrofit 9mm belts.
How will you align the two X and Y axis rails so they are parallel?
We're not talking about hanging pictures on a wall here. You need the ends of the rails aligned within 0.1 mm or better for the linear guides to move freely. How wide is the line that those levels produce, how accurate is the 90 degree relationship between the lines, and how repeatable is the leveling?
says self leveling accuracy is +/- 4 degrees. Ugh!