Hi Martin,

With those friends then your sorted and just need a decent design that's tailored to your requirements. It's not difficult really and a lot easier if you can narrow the use to a specific area like Woods, plastics etc. If your wanting a machine that cuts everything IE: Soft and Semi hard materials like Aluminium then it gets more critical regards design.
To build an all-round-machine then really it will most likely be "Jack of all trades master of none" and it's very very difficult to build a machine that excels at everything.
I find from experience that you get a much better machine with an easier build if you identify your Main need and build to suit that need.

Now from what your saying wood use will be your main Use and that makes building decent DIY machine much easier has the tolerances and strength required for wood are much less than say cutting Aluminium or cutting to Very fine engraving tolerances.
Now I'm not saying you can just throw it together and still needs certain amount of care to design and attention to build quality but the it's much less forgiving.

If you have experienced Welders and Grinding services available then it will certainly help big time regards build accuracy you then just need a design that suits your requirement best and correct choice of components.

Post your ideas and lets have look.!!

Good luck.