I have a homebrew cnc with a fairly similar design, and can cut anything up through mild steel on it. The steel cuts don't have great tolerances, get something

I have a homebrew cnc with a fairly similar design, and can cut anything up through mild steel on it. The steel cuts don't have great tolerances, get something around .005" rail deflection at the extreme, but it's amazing what some extrusion can do if you have a decent spindle.