BUILD LOG: CNC In A Box

Thought I'd start mesel' a Build Log, so when I have a bunch of stupid questions, there's something to refer to. Although this is in the Router Logs forum, I currently live in hope that it'll be able to do a bit of aluminium.

Some specs first, partly because I currently don't have a machine running SketchUp.

Cutting area: about A3 (420mmx297mm) and around 200mm of Z axis travel.

Outside dimensions: I really want to make it so that it can be packed away into a 146L Really Useful Box after use, with minimal work (hopefully just lowering the Z-axis and lifting it in). That means 700mmx545mmx400mm, which affects a lot of design decisions.

Steppers and drivers: Zapp's 3-Axis 3Nm kit.

Y-axis: dual leadscrews, driven by pulleys from 1 stepper, moving a gantry mounted on supported round rails (20mm?)

X-axis: on the gantry, single leadscrew driven by a pulley from the stepper. Not sure if the round rails will be supported or unsupported, again 20mm.

Z-axis: single leadscrew driven by - you guessed - a pulley. The rails and leadscrew mounted on the router mount, and the bearings/nut attached to the X-axis. Unsupported rails, 20mm.

The machine frame is mostly to be aluminium profile.

Can't think of much more to add at the moment ...

Chris.