Thanks. Some nice ideas there. Perhaps a little bigger than I had in mind though.

A few of questions:

I appreciate that there is no definitive answer and that part quality, precision & tolerance is down to the choice of components. However taking into account my original requirements of being able to machine PCBs, profile sheet aluminium, and carbon fibre sheet on a machine with a 200mx300mm bed what sort of spec stepper motor (NEMA 23?), spindle and slide rails should I be looking at?

Would I be better off with a 12mm supported round rail, something like SBR12 or a 15 'square' rail with slide blocks such as MGN15 ?

Thanks