Designed for Vertical X-axis competition.PCB manufacture needs to be easier for reprap; countless numbers of printed parts can be made, but I see electronics as a real bottleneck. Just like 3D printing, the more accessible it is, the better the take up. To this end, I have started designing a milling carriage for the Vertical X-axis standard.The idea is that the normal x-carriage can be unclipped from the x-axis, leaving LM8UU bearings on the linear rods, then this one can be clipped on to mill PCBs or other small parts.Basic reprap PCB milling page here: http://reprap.org/wiki/PCB_Milling Linear mounts are 70mm apart, as per the standard http://reprap.org/wiki/Vertical_X_Axis_Standard. The LM8UU Linear bearing mounts were taken from Josef Průša/Greg Frost's X-end holders, which I think have the best grip on the bearings: http://github.com/prusajr/PrusaMendel. I guess my idea is that it could be swapped, not that you'd be doing it every day. I have found Greg's other design http://www.thingiverse.com/thing:9871 doesn't have as strong a hold, and is more difficult to print reliably (lots of small towers). Spindle layout is based on David Carr's Mantis 9 Low Cost Spindle v2.0 http://makeyourbot.org/low-cost-spindle-2-0. The carriage will incorporate the belt doubling system from Madkite http://www.thingiverse.com/thing:8852 that Emmanuel is building into the Vertical X-axis he has designed http://reprap.org/wiki/X-carriage-struder and http://www.thingiverse.com/thing:10711 More details to follow on vitamins required, once I work them out!It's not ready to be printed yet. STLs generated by the .scad file need fixing (I used Netfabb Basic edition). Spacing needs to be refined, but it's a start. There are no belt mounts at present.I see the main problems using a reprap for milling as: Any observations, comments and/or suggestions gratefully received!