My first CNC router, made from the scratch. Ideas, opinions, hints are welcomed

Hi! First of all, sorry for my rough english, I'll try to do my best

I'm planning my first CNC, and I want to make it on my way, an extra effort to full understanding of how this machines works. I'm using Inkscape and FreeCAD, because are Free (GPL) and easy to use.

In short, my goals are:

- 600mm*600mm*150mm working area.
- Low budget.
- Simplicity and versatility.
- Completely custom, from the scratch. No OX and other derivates.
- A special...

My first CNC router, made from the scratch. Ideas, opinions, hints are welcomed