It seems you have joined the ranks of those who bought tiny machines in the hope of producing useful parts.It isn't impossible,but it won't be quick....
They are quite useful for getting to grips with the processes of CNC machining and maybe producing small parts from soft wood.The design you have put forward will be a big step up once its working.I would be a little concerned about the leverage on the spindle bracket and might go as far as sawing it in half with each smaller section moved as far apart as is practical.
It looks as though you intend to use a fairly tall machine and this complicates things as far as rigidity goes.I suggest you add to the spindle in your design a collet nut and a tool and then take a look at how close the machine will approach a vertical wall in all directions without fouling,it might surprise you.It will also give an idea of how steep a slope is feasible if you try 3D surfacing.Good luck with the project.