Guys , I was debating to build a Joe's CNC , and while Joes V bearing Evolution is all that I would probably ever require, the more I study , I'm certain I could build a cnc table myself using square block linear rails , and CNCRP pro series rack and pinion .
Sorry if my terminology isn't great yet .

My design was to have a cutting area of 4' x 5' , as a 4/8 will not fit well in my garage . I'm interested in 3D carvings and signs , and fairly good repeatability. Will be using Nema34 for steppers , aluminum extrusion most likely from Vancouver , as I'm located in eastern BC Canada .

Was hoping to get get opinions on these linear guides and blocks in this link below .

https://motionconstrained.com/store/...linear-guides/

I'm not sure if this is there lower model ? I have heard where 25mm are overkill and 20mm are fine , but I would prefer to go with these , as the cost difference isn't a lot.
Also heard mention that you should exceed your cutting area by approx a foot on each axis for the linear guide length in order to compensate for the area lost to the blocks .

Thanks in advance all , as I've gotta start somewhere