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I am in the planning stages of a potential large format 3D Printer build, and want some input. I am considering what the best budget option for the linear slides/ rails is. Currently, here are my options, and the pros/cons:

Aluminum t slot with v bearings: more expensive, possibly higher accuracy
Aluminum square tubing with 3d printed bearing blocks that clamp 608 skateboard bearings to all sides
EMT conduit with 608 bearings like the MPCNC
12mm metal rods with linear bearings
Supported linear rail with bearings

What are your thoughts?

I plan to build the machine in a gantry style that takes design aspects from cnc machines that have a stationary bed. I hope to eventually equip it with a E3D Volcano or Supervolcano hotend, and a diy Pellet extruder for recycling old prints, and printing with cheap pellets. As for a heated bed, I will likely be using multiple smaller heated beds tied together and powered through some relays. I am also considering having dual control boards with a multiplexer/ demultiplexer circuit to switch the stepper and endstop wiring between control boards. This would enable me to run a 32 bit control board for 3d printing, and have the option to switch control over to an arduino uno with a GRBL shield for cnc milling and laser cutting. I have never seen anyone do a dual control board setup before. This is the best way I know of to achieve the dual function, other than building a custom PCB, or switching firmware for different uses. Please let me know if you are aware of a better way of doing this. For now, I am working with a budget of $500 USD to get a working printer with the volcano hodtnd, and adding on features as I go.

Any ideas are appreciated as always