CNC machines and moulds

Hi guys,
I’m just starting my journey the precious plastics.  Im working with a couple of colleagues to build the shredder and other machines.  Ive just made a mini foundry to melt aluminium to cast moulds using sandcasting but was looking at the potential for a small scale desktop cnc milling machine.
To that end I have a few questions:
Has anyone already done this? what problems did you encounter? the strength of the chassis on cheaper machines seems a little suspect and could lead to poor milling although this youtube clip seems to have got very impressive accuracy on his cheap (apparently) home machine.

Secondly, does anyone know of a place where we can share cnc mould files?  It seems silly for everyone to be reinventing the wheel if theres an open forum to share!


I found around the internet a tone of CNC done mostly with 3D printed parts.
Actually I think this will be my project for this summer xDD.

This one seems pretty legit to do with low budget, dunno, but as said is plenty of it out there: