Hi all! New to CNC first project 8x4 machine!

Hi
Im Toby and have been watching this forum for awhile now with the intention of signing up.
I come from woodworking and joinery background and recently my Dad who runs his own workshop wants to adapt and change his workshop to included a CNC to be more competitive with his pricing.

We are looking to build/buy a cnc machine to cut 8x4 material of wood, acrylics and light work non ferrous metals. Ww have the room and 3phase power. With our background in wood we found on youtube"How to Build a CNC Router On A Shoestring Budget" by cncsidewinder and due to his project being built in wood and with no experience with metal work we were drawn to his project and plans.


But to upscale this to be able to cut 8x4 we are looking for your help, wisdom and education?

Will it be unstable at a greater distance? do we use something different to ballscrew?