careful bud .....that utube vid looks like welded steel and more importantly has 20mm precision rail and carriages (thk, etc.) add the power cable cable management and that is one expensive machine.

You Will not be able to achieve the same results with the carriages you propose to use. dont get me wrong I'm not trying to put you off. i want to help

maybe take a step back and ask your self exaclty what you whant to cut and performance you need.

how much do the carridges work out at? they dont seem that cheap. are you going to grind the contact surface of the running bar?

anyway look forward to the following drawings....