3 kN for engraving? I got to be deep text then.
Even the smallest linear guides takes the load, you can run one single rail with one or two carriers. They are very tight and with a ballscrew you'll have no problems keeping the tolerances, if we talk inches though (Microns of a mm is caused by temperature).
I suggest you check old threads in the other forums, for example in the
Engraving and the
Metalworking machines-subforums.
Regards,
Sven