Noobquestion: how do i design a cnc machine?

Hi all,

i'm looking to build myself a very basic mill. Mostly it's a proof-of-concept for me and therefor i really want to do just about everything myself. Even the design.

I've browsed the web for a couple of weeks now and i've seen a large number of different designs and i have a general idea of what materials i intend to use for my first CNC machine and i have a rough idea on a design. However i really want to plan first instead of buying parts and materials randomly and eventually figuring out that i needed something entirely different or that a certain element really should've been sized different.

Are there any programs out there that a newbie can easily get accustomed to in order to design a cnc machine? I'm not entirely new to 3D modeling (i've done some 3DsMax in the past) but i haven't really kept up with all the different programs out there for the past 15 years. I'm currently using a Mac (but if need be i could find a windows machine although i'd rather not) so preferably it'd have to be a Mac program.

Ideally the program allows me to design the machine, gives me a good 3D representation and maybe even allows for printing of patterns? I'd really like to keep the costs down on the program itself too.

Thanks in advance,

Sebastiaan