New and in need of wisdom

[Washout]

Hi all,

Been lurking for a while and as I'm about to get an extension to the man cave, I'll be filling that with a new toy.

I've been making things out of aluminium and mild steel mostly (some stainless as well when needed) for a variety of projects for a number of years, but only having basic tools and a bench drill is limiting what I can achieve (especially in terms of accuracy). So I'm looking to buy or make a CNC mill, which I also want to double up as a 3d printer by swapping out the spindle with an ABS extruder and tossing a heated plate on the bed. I've also been 3d modelling/CAD'ing for a number of years (some PC sim/games related) and use a variety of software dependant on what I want to do and how quickly e.g. AutoCAD, Blender, Sketchup, 3DMax and some proprietry stuff.

Ideally I'd like a 600-1000mm by 400-500mm bed and a fair bit of Z travel for sculpting/3d printing work and I will likely be getting a 4th axis in a few months after initial purchase. Work will be predominantly in Aluminium (6061 T4/6 mainly but may need some harder/stronger) with occasional mild steel and some ABS and other plastics.

The options I have been toying with after reading here for a while are:

1. Buying a ready made CNC mill from the UK - expensive and from what I've seen of machines like the Heiz etc they are generally not using supported rails and some other components I read on here should be almost mandatory.
2. Buy a cheap chinese ebay machine such as the 6040 - would buy in the knowledge it will need some or most of its electronics replacing and supported rails in the Y and Z axis.
3. Design and build my own machine from scratch - longer lead time and some additional digging around for components, although thanks to some of the build logs I have already got most sourced e.g. extrusions, rails, ball screws etc.

I have almost discounted option 1, as I haven't seen anything that doesn't look like I'm tossing 100% mark up at the builder and I'm the kind of person that fixes things myself rather than enduring the frustrations of after market support.

Option 3 is appealling, but my main concern is I don't have the kind of tools that I think will achieve the kind of accuracy I think I need to avoid things like binding on rails/ballscrews due to misalignment from imprecise drilling. I also don't have welding kit and have very limited experience in this.

Option 2 is looking favourite at the moment therefore and even if I double the cost by upgrading then I'll still be around my budget.

Just in case I'm worrying about option 2 needlessly I have the following design I whipped up over a couple of hours in Sketchup, which if anyone has the time would like feedback on (most of the extrusions are 30mm or derivatives of) and the bed is 1000mm by 500mm to give an idea of scale but happy to send anyone the .skp if they want to dig further/look around:

Thanks in advance.